Question

tính a, (2x^2 + 3y)^3 ; b, (1/2x - 3)^3 mong các bn giúp đỡ mk

Answer 1

a: \(\left(2x^2+3y\right)^3\)

\(=\left(2x^2\right)^3+3\cdot\left(2x^2\right)^2\cdot3y+3\cdot2x^2\cdot\left(3y\right)^2+\left(3y\right)^3\)

\(=8x^6+9y\cdot4x^4+6x^2\cdot9y^2+27y^3\)

\(=8x^6+36x^4y+54x^2y^2+27y^3\)

b: \(\left(\dfrac{1}{2}x-3\right)^3\)

\(=\left(\dfrac{1}{2}x\right)^3-3\cdot\left(\dfrac{1}{2}x\right)^2\cdot3+3\cdot\dfrac{1}{2}x\cdot3^2-3^3\)

\(=\dfrac{1}{8}x^3-\dfrac{9}{4}x^2+\dfrac{27}{2}x-27\)