Based on the problem number 3 what is the difference of the areas of two squares respectively

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Based on the problem number 3 what is the difference of the areas of two squares respectively

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Option 2 : 9 cm

Based on the problem number 3 what is the difference of the areas of two squares respectively

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Based on the problem number 3 what is the difference of the areas of two squares respectively

Let longer segment and smaller segment be M and N respectively.

Given,

Area of square with M segment – area of square with N segment = 32

And,

⇒ M – N = 2

Then,

⇒ M2 – N2 = 32

⇒ (M – N)(M + N) = 32

⇒ M + N = 16

Solving equations,

⇒ 2M = 18

⇒ M = 9 cm

⇒ N = 7 cm

∴ Length of greater line segment is 9 cm.

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A quadratic equation is a second degree polynomial usually in the form of f(x) = ax2 + bx + c where a, b, c, ∈ R, and a ≠ 0. The term ‘a’ is referred to as the leading coefficient, while ‘c’ is the absolute term of f (x). Every quadratic equation has two values of the unknown variable, usually known as the roots of the equation (α, β).

What is Difference of Squares?

The difference of two squares is a theorem that tells us if a quadratic equation can be written as a product of two binomials, in which one shows the difference of the square roots and the other shows the sum of the square roots.

One thing to note about this theorem is that it does not apply to the SUM of squares.

Difference of Squares Formula

The difference of square formula is an algebraic form of the equation used to express the differences between two square values. A difference of square is expressed in the form:

a2 – b2, where both the first and last term is perfect squares. Factoring the difference of the two squares gives:

a2 – b2 = (a + b) (a – b)

This is true because, (a + b) (a – b) = a2 – ab + ab – b2 = a2 – b2

How to Factor Difference of Squares?

In this section, we will learn how to factorize algebraic expressions using the difference of square formula. To factor a difference of squares, the following steps are undertaken:

  • Check if the terms have the greatest common factor (GCF) and factor it out. Remember to include the GCF in your final answer.
  • Determine the numbers that will produce the same results and apply the formula: a2– b2 = (a + b) (a – b) or (a – b) (a + b)
  • Check whether you can factor the remaining terms any further.

Let’s solve a few examples by applying these steps.

Example 1

Factor 64 – x2

Solution

Since we know the square of 8 is 64, then we can rewrite the expression as;
64 – x2 = (8)2 – x2
Now, apply the formula a2 – b2 = (a + b) (a – b) to factorize expression;
= (8 + x) (8 – x).

Example 2

Factorize
x 2 −16

Solution

Since x2−16 = (x) 2− (4)2, therefore apply the difference square formula a2 – b2 = (a + b) (a – b), where a and b in this case are x and 4 respectively.

Therefore, x2 – 42 = (x + 4) (x – 4)

Example 3

Factor 3a2 – 27b2

Solution

Since 3 is GCF of the terms, we factor it out.
3a2 – 27b2 = 3(a2 – 9b2)
=3[(a)2 – (3b)2]
Now apply a2 – b2 = (a + b) (a – b) to get;
= 3(a + 3b) (a – 3b)

Example 4

Factor x3 – 25x
Solution

Since the GCF = x, factor it out;
x3 – 25x = x (x2 – 25)
= x (x2 – 52)
Apply the formula a2 – b2 = (a + b) (a – b) to get;
= x (x + 5) (x – 5).

Example 5

Factor the expression (x – 2)2 – (x – 3)2

Solution

In this problem a = (x – 2) and b = (x – 3)

We now apply a2 – b2 = (a + b) (a – b)

= [(x – 2) + (x – 3)] [(x – 2) – (x – 3)]

= [x – 2 + x – 3] [x – 2 – x + 3]

Combine the like terms and simplify the expressions;

[x – 2 + x – 3] [x – 2 – x + 3] = > [2x – 5] [1]

= [2x – 5]

Example 6

Factor the expression 25(x + y)2 – 36(x – 2y)2.

Solution

Rewrite the expression in the form a2 – b2.

25(x + y)2 – 36(x – 2y)2 => {5(x + y)}2 – {6(x – 2y)}2
Apply the formula a2 – b2 = (a + b) (a – b) to get,

= [5(x + y) + 6(x – 2y)] [5(x + y) – 6(x – 2y)]

= [5x + 5y + 6x – 12y] [5x + 5y – 6x + 12y]

Collect like terms and simplify;

= (11x – 7y) (17y – x).

Example 7

Factor 2x2– 32.

Solution

Factor out the GCF;
2x2– 32 => 2(x2– 16)
= 2(x2 – 42)

Applying the difference squares formula, we get;
= 2(x + 4) (x – 4)

Example 8

Factor 9x6 – y8

Solution

First, rewrite 9x6 – y8 in the form a2 – b2.

9x6 – y8 => (3x3)2 – (y4)2

Apply a2 – b2 = (a + b) (a – b) to get;

= (3x3 – y4) (3x3 + y4)

Example 9

Factor the expression 81a2 – (b – c)2

Solution

Rewrite 81a2 – (b – c)2 as a2 – b2
= (9a)2 – (b – c)2
By applying the formula of a2 – b2 = (a + b) (a – b) we get,= [9a + (b – c)] [9a – (b – c)]

= [9a + b – c] [9a – b + c ]

In mathematics, the difference of two squares is a squared (multiplied by itself) number subtracted from another squared number. Every difference of squares may be factored according to the identity

a 2 − b 2 = ( a + b ) ( a − b ) {\displaystyle a^{2}-b^{2}=(a+b)(a-b)}
Based on the problem number 3 what is the difference of the areas of two squares respectively

in elementary algebra.

The proof of the factorization identity is straightforward. Starting from the left-hand side, apply the distributive law to get

( a + b ) ( a − b ) = a 2 + b a − a b − b 2 {\displaystyle (a+b)(a-b)=a^{2}+ba-ab-b^{2}}  

By the commutative law, the middle two terms cancel:

b a − a b = 0 {\displaystyle ba-ab=0}  

leaving

( a + b ) ( a − b ) = a 2 − b 2 {\displaystyle (a+b)(a-b)=a^{2}-b^{2}}  

The resulting identity is one of the most commonly used in mathematics. Among many uses, it gives a simple proof of the AM–GM inequality in two variables.

The proof holds in any commutative ring.

Conversely, if this identity holds in a ring R for all pairs of elements a and b, then R is commutative. To see this, apply the distributive law to the right-hand side of the equation and get

a 2 + b a − a b − b 2 {\displaystyle a^{2}+ba-ab-b^{2}}  .

For this to be equal to a 2 − b 2 {\displaystyle a^{2}-b^{2}}  , we must have

b a − a b = 0 {\displaystyle ba-ab=0}  

for all pairs a, b, so R is commutative.

 

The difference of two squares can also be illustrated geometrically as the difference of two square areas in a plane. In the diagram, the shaded part represents the difference between the areas of the two squares, i.e. a 2 − b 2 {\displaystyle a^{2}-b^{2}}  . The area of the shaded part can be found by adding the areas of the two rectangles; a ( a − b ) + b ( a − b ) {\displaystyle a(a-b)+b(a-b)}  , which can be factorized to ( a + b ) ( a − b ) {\displaystyle (a+b)(a-b)}  . Therefore, a 2 − b 2 = ( a + b ) ( a − b ) {\displaystyle a^{2}-b^{2}=(a+b)(a-b)}  .

Another geometric proof proceeds as follows: We start with the figure shown in the first diagram below, a large square with a smaller square removed from it. The side of the entire square is a, and the side of the small removed square is b. The area of the shaded region is a 2 − b 2 {\displaystyle a^{2}-b^{2}}  . A cut is made, splitting the region into two rectangular pieces, as shown in the second diagram. The larger piece, at the top, has width a and height a-b. The smaller piece, at the bottom, has width a-b and height b. Now the smaller piece can be detached, rotated, and placed to the right of the larger piece. In this new arrangement, shown in the last diagram below, the two pieces together form a rectangle, whose width is a + b {\displaystyle a+b}   and whose height is a − b {\displaystyle a-b}  . This rectangle's area is ( a + b ) ( a − b ) {\displaystyle (a+b)(a-b)}  . Since this rectangle came from rearranging the original figure, it must have the same area as the original figure. Therefore, a 2 − b 2 = ( a + b ) ( a − b ) {\displaystyle a^{2}-b^{2}=(a+b)(a-b)}  .  

The formula for the difference of two squares can be used for factoring polynomials that contain the square of a first quantity minus the square of a second quantity. For example, the polynomial x 4 − 1 {\displaystyle x^{4}-1}   can be factored as follows:

x 4 − 1 = ( x 2 + 1 ) ( x 2 − 1 ) = ( x 2 + 1 ) ( x + 1 ) ( x − 1 ) {\displaystyle x^{4}-1=(x^{2}+1)(x^{2}-1)=(x^{2}+1)(x+1)(x-1)}  

As a second example, the first two terms of x 2 − y 2 + x − y {\displaystyle x^{2}-y^{2}+x-y}   can be factored as ( x + y ) ( x − y ) {\displaystyle (x+y)(x-y)}  , so we have:

x 2 − y 2 + x − y = ( x + y ) ( x − y ) + x − y = ( x − y ) ( x + y + 1 ) {\displaystyle x^{2}-y^{2}+x-y=(x+y)(x-y)+x-y=(x-y)(x+y+1)}  

Moreover, this formula can also be used for simplifying expressions:

( a + b ) 2 − ( a − b ) 2 = ( a + b + a − b ) ( a + b − a + b ) = ( 2 a ) ( 2 b ) = 4 a b {\displaystyle (a+b)^{2}-(a-b)^{2}=(a+b+a-b)(a+b-a+b)=(2a)(2b)=4ab}  

Complex number case: sum of two squares

The difference of two squares is used to find the linear factors of the sum of two squares, using complex number coefficients.

For example, the complex roots of z 2 + 4 {\displaystyle z^{2}+4}   can be found using difference of two squares:

z 2 + 4 {\displaystyle z^{2}+4}   = z 2 − 4 i 2 {\displaystyle =z^{2}-4i^{2}}   (since i 2 = − 1 {\displaystyle i^{2}=-1}  ) = z 2 − ( 2 i ) 2 {\displaystyle =z^{2}-(2i)^{2}}   = ( z + 2 i ) ( z − 2 i ) {\displaystyle =(z+2i)(z-2i)}  

Therefore, the linear factors are ( z + 2 i ) {\displaystyle (z+2i)}   and ( z − 2 i ) {\displaystyle (z-2i)}  .

Since the two factors found by this method are complex conjugates, we can use this in reverse as a method of multiplying a complex number to get a real number. This is used to get real denominators in complex fractions.[1]

Rationalising denominators

The difference of two squares can also be used in the rationalising of irrational denominators.[2] This is a method for removing surds from expressions (or at least moving them), applying to division by some combinations involving square roots.

For example: The denominator of 5 3 + 4 {\displaystyle {\dfrac {5}{{\sqrt {3}}+4}}}   can be rationalised as follows:

5 3 + 4 {\displaystyle {\dfrac {5}{{\sqrt {3}}+4}}}   = 5 3 + 4 × 3 − 4 3 − 4 {\displaystyle ={\dfrac {5}{{\sqrt {3}}+4}}\times {\dfrac {{\sqrt {3}}-4}{{\sqrt {3}}-4}}}   = 5 ( 3 − 4 ) ( 3 + 4 ) ( 3 − 4 ) {\displaystyle ={\dfrac {5({\sqrt {3}}-4)}{({\sqrt {3}}+4)({\sqrt {3}}-4)}}}   = 5 ( 3 − 4 ) 3 2 − 4 2 {\displaystyle ={\dfrac {5({\sqrt {3}}-4)}{{\sqrt {3}}^{2}-4^{2}}}}   = 5 ( 3 − 4 ) 3 − 16 {\displaystyle ={\dfrac {5({\sqrt {3}}-4)}{3-16}}}   = − 5 ( 3 − 4 ) 13 . {\displaystyle =-{\dfrac {5({\sqrt {3}}-4)}{13}}.}  

Here, the irrational denominator 3 + 4 {\displaystyle {\sqrt {3}}+4}   has been rationalised to 13 {\displaystyle 13}  .

Mental arithmetic

The difference of two squares can also be used as an arithmetical short cut. If two numbers (whose average is a number which is easily squared) are multiplied, the difference of two squares can be used to give you the product of the original two numbers.

For example:

27 × 33 = ( 30 − 3 ) ( 30 + 3 ) {\displaystyle 27\times 33=(30-3)(30+3)}  

Using the difference of two squares, 27 × 33 {\displaystyle 27\times 33}   can be restated as

a 2 − b 2 {\displaystyle a^{2}-b^{2}}   which is 30 2 − 3 2 = 891 {\displaystyle 30^{2}-3^{2}=891}  .

Difference of two consecutive perfect squares

The difference of two consecutive perfect squares is the sum of the two bases n and n+1. This can be seen as follows:

( n + 1 ) 2 − n 2 = ( ( n + 1 ) + n ) ( ( n + 1 ) − n ) = 2 n + 1 {\displaystyle {\begin{array}{lcl}(n+1)^{2}-n^{2}&=&((n+1)+n)((n+1)-n)\\&=&2n+1\end{array}}}  

Therefore, the difference of two consecutive perfect squares is an odd number. Similarly, the difference of two arbitrary perfect squares is calculated as follows:

( n + k ) 2 − n 2 = ( ( n + k ) + n ) ( ( n + k ) − n ) = k ( 2 n + k ) {\displaystyle {\begin{array}{lcl}(n+k)^{2}-n^{2}&=&((n+k)+n)((n+k)-n)\\&=&k(2n+k)\end{array}}}  

Therefore, the difference of two even perfect squares is a multiple of 4 and the difference of two odd perfect squares is a multiple of 8.

Factorization of integers

Several algorithms in number theory and cryptography use differences of squares to find factors of integers and detect composite numbers. A simple example is the Fermat factorization method, which considers the sequence of numbers x i := a i 2 − N {\displaystyle x_{i}:=a_{i}^{2}-N}  , for a i := ⌈ N ⌉ + i {\displaystyle a_{i}:=\left\lceil {\sqrt {N}}\right\rceil +i}  . If one of the x i {\displaystyle x_{i}}   equals a perfect square b 2 {\displaystyle b^{2}}  , then N = a i 2 − b 2 = ( a i + b ) ( a i − b ) {\displaystyle N=a_{i}^{2}-b^{2}=(a_{i}+b)(a_{i}-b)}   is a (potentially non-trivial) factorization of N {\displaystyle N}  .

This trick can be generalized as follows. If a 2 ≡ b 2 {\displaystyle a^{2}\equiv b^{2}}   mod N {\displaystyle N}   and a ≢ ± b {\displaystyle a\not \equiv \pm b}   mod N {\displaystyle N}  , then N {\displaystyle N}   is composite with non-trivial factors gcd ( a − b , N ) {\displaystyle \gcd(a-b,N)}   and gcd ( a + b , N ) {\displaystyle \gcd(a+b,N)}  . This forms the basis of several factorization algorithms (such as the quadratic sieve) and can be combined with the Fermat primality test to give the stronger Miller–Rabin primality test.

 

Vectors a (purple), b (cyan) and a + b (blue) are shown with arrows

The identity also holds in inner product spaces over the field of real numbers, such as for dot product of Euclidean vectors:

a ⋅ a − b ⋅ b = ( a + b ) ⋅ ( a − b ) {\displaystyle {\mathbf {a} }\cdot {\mathbf {a} }-{\mathbf {b} }\cdot {\mathbf {b} }=({\mathbf {a} }+{\mathbf {b} })\cdot ({\mathbf {a} }-{\mathbf {b} })}  

The proof is identical. For the special case that a and b have equal norms (which means that their dot squares are equal), this demonstrates analytically the fact that two diagonals of a rhombus are perpendicular. This follows from the left side of the equation being equal to zero, requiring the right side to equal zero as well, and so the vector sum of a + b (the long diagonal of the rhombus) dotted with the vector difference a - b (the short diagonal of the rhombus) must equal zero, which indicates the diagonals are perpendicular.

Difference of two nth powers

 

Visual proof of the differences between two squares and two cubes

If a and b are two elements of a commutative ring R, then a n − b n = ( a − b ) ( ∑ k = 0 n − 1 a n − 1 − k b k ) {\displaystyle a^{n}-b^{n}=\left(a-b\right)\left(\sum _{k=0}^{n-1}a^{n-1-k}b^{k}\right)}  .

Historically, the Babylonians used the difference of two squares to calculate multiplications. [3]

For example:

93 x 87 = 90² - 3² = 8091

64 x 56 = 60² - 4² = 3584

  • Congruum, the shared difference of three squares in arithmetic progression
  • Conjugate (algebra)
  • Factorization

  1. ^ Complex or imaginary numbers TheMathPage.com, retrieved 22 December 2011
  2. ^ Multiplying Radicals TheMathPage.com, retrieved 22 December 2011
  3. ^ "Babylonian mathematics".

  • Stanton, James Stuart (2005). Encyclopedia of Mathematics. Infobase Publishing. p. 131. ISBN 0-8160-5124-0.
  • Tussy, Alan S.; Gustafson, Roy David (2011). Elementary Algebra (5th ed.). Cengage Learning. pp. 467–469. ISBN 978-1-111-56766-8.
  • difference of two squares at mathpages.com

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