Advertisements
Advertisements
Question
Simplify: (2x + 3y)3 - (2x - 3y)3
Sum
Solution
Using the formula a3 - b3 = (a - b)(a2 + ab + b2)
∴ (2x + 3y)3 - (2x - 3y)3
= [(2x + 3y) - (2x - 3y)][(2x + 3y)2 + (2x + 3y)(2x - 3y) + (2x - 3y)2]
= [2x + 3y - 2x + 3y][4x2 + 12xy + 9y2 + 4x2 - 9y2 + 4x2 - 12xy + 9y2]
= 6y(12x2 + 9y2)
= 72x2y + 54y3
shaalaa.com
Is there an error in this question or solution?
