Question

Expand (2x+3y)³ in desceding power of x ?

Answer 1

`(2x+3y)^3=8x^3+36x^2y+54xy^2+27y^3`

Explanation:

Expansion of `(a+b)^3` in decreasing powers of `a` is `a^3+3a^2b+3ab^2+b^3`

Hence `(2x+3y)^3`

= `(2x)^3+3*(2x)^2*3y+3*2x*(3y)^2+(3y)^3`

= `8x^3+36x^2y+54xy^2+27y^3`