Question

khai trien 

a) ( 2 phan 5 x + 5y)³

b) ( x phan 3 + y phan 2 )³

c) (x^m + yⁿ)³ 

Answer 1

a) \(=\) \(\left(\dfrac{2}{5}\right)^3+3\left(\dfrac{2}{5}\right)^25y+3\left(\dfrac{2}{5}\right)\left(5y\right)^2+\left(5y\right)^3\)

\(=\dfrac{8}{125}+\dfrac{12}{5}y+30y^2+125y^3\)

b) \(=\left(\dfrac{x}{3}\right)^3+3\left(\dfrac{x}{3}\right)^2.\left(\dfrac{y}{2}\right)+3\left(\dfrac{x}{3}\right).\left(\dfrac{y}{2}\right)^2+\left(\dfrac{y}{2}\right)^3\)

\(=\) \(\dfrac{x^3}{27}+\dfrac{x^2y}{6}+\dfrac{xy^2}{2}+\dfrac{y^3}{8}\)

c) \(=\) \(\left(x^m\right)^3+3.\left(x^m\right)^2.y^n+3.x^m.\left(y^n\right)^2+\left(y^n\right)^3\)

\(=x^{m+3}+3.x^{m+2}.y^n+3.x^m.y^{n+2}+y^{n+3}\)