SSC (English Medium) Class 8Maharashtra State Board
Share

# Simplify (5x − 7y)3 + (5x + 7y)3 - SSC (English Medium) Class 8 - Mathematics

ConceptExpansion of (A + B + C)2

#### Question

Simplify

(5x − 7y)+ (5x + 7y)3

#### Solution

It is known that,

$\left( a + b \right)^3 = a^3 + b^3 + 3 a^2 b + 3a b^2 ; \left( a - b \right)^3 = a^3 - b^3 - 3 a^2 b + 3a b^2$

$\ \left( 5x - 7y \right)^3 + \left( 5x + 7y \right)^3$

$= \left( 5x \right)^3 - \left( 7y \right)^3 - 3 \times \left( 5x \right)^2 \times 7y + 3 \times 5x \times \left( 7y \right)^2 + \left( 5x \right)^3 + \left( 7y \right)^3 + 3 \times \left( 5x \right)^2 \times \left( 7y \right) + 3 \times 5x \times \left( 7y \right)^2$ $= 125 x^3 - 343 y^3 - 525 x^2 y + 735x y^2 + 125 x^3 + 343 y^3 + 525 x^2 y + 735x y^2$ $= 250 x^3 + 1470x y^2$

Is there an error in this question or solution?

#### APPEARS IN

Balbharati Solution for Balbharati Class 8 Mathematics (2019 to Current)
Chapter 5: Expansion formulae
Practice set 5.3 | Q: 2.4 | Page no. 27
Solution Simplify (5x − 7y)3 + (5x + 7y)3 Concept: Expansion of (A + B + C)2.
S