Question

⏩★hi friends★⏪

(5x-7y)(5x+7y)-2(x-2y)²
Answer behind is 23x²+8xy-57y²
let's see who can solve it! No spam❌...correct answer will be marked as brainliest!

Answer 1

Here your answer goes

Step :- 1

Given ,

$( 5x - 7y ) ( 5x + 7y ) - 2 ( x - 2y )^{2}$

Here Separate the equation into three parts :-

( 5x - 7y ) ===>> x

( 5x + 7y ) ===>> y

2 - (x - 2y )^2 ===>> z

Step :- 2

As you can see there is only a Sign difference between x and y

Write the equation (x) ,and (y) together

( 5x - 7y ) ( 5x + 7y )

As you can see it is in the form (a -b ) (a + b ) which is equal to a^ - b^2

So , we can write it as $(5x)^2 - (7y)^2$ -------->> $x_{1}$

Step :- 3

Write $x_{1}$ and z together

$(5x)^2 - (7y)^2 - 2(x - 2y)^2$

⇒ $25x^2 - 49y^2 - 2(x^2 + 4y^2 - 4xy)$

⇒ $25x^2 - 49y^2 - 2x^2 - 8y^2 + 8xy$

⇒ $23x^2 + 8xy - 57y^2$

↓↓↓

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Answer 2

(5x-7y)(5x+7y)-2(x-2y)²

Applying identity on frst two

(a-b)(a+b)=$a{}^{2} - b{}^{2}$

We get

[Tex](25x{}^{2} - 49y{}^{2})-2(x-2y)²[/tex]

[Tex] (25x{}^{2} - 49y{}^{2}) -2(x² - 4xy + 4y² )[/tex]

$25x{}^{2} - 49y{}^{2}-2x{}^{2}+8xy-8y{}^{2}$

Adding and subtracting

[Tex] 23{}^{2} +8xy -57y{}^{2} [/tex]

As prr your answer

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