Question

simplify :(2x-5y) 3 - (2x+5y) 3

Answer 1

hi mate,

(2x-5y)³-(2x+5y)³

a³-b³ = (a-b)(a²+b²+ab)

=> (2x-5y-2x-5y)[{2x-5y}²+{2x+5y}²+(2x-5y)(2x+5y)]

=> -10y(4x²+25y²-20xy+ 4x²+25y²+20xy+4x²-25y²)

(a+b)(a-b) = a²-b²

= -10y(12x²+25y²)

i hope it helps you.