Câu 1:(x+1/3)^2 Câu2: ( 2x +y^2)^3 Câu3: (1/2x^2 +1/4y)^3 Câu 4: (3x^2 -2y)^3 Câu 5: (2/3x^2 -1/2y)^3

Đáp án+giải thích các bước giải:

C1:

(x+$\dfrac{1}{3}$)²=x²+2.x.$\dfrac{1}{3}$+ ($\dfrac{1}{3}$)²

=x²+ $\dfrac{2}{3}$ + $\dfrac{1}{9}$

C2:

(2x+y²)³=(2x)³+3.(2x)².y²+ 3.2x.$y^{4}$+$y^{6}$

=8x³+12x²y²+6x$y^{4}$+ $y^{6}$

C3:

($\dfrac{1}{2}$x²+ $\dfrac{1}{4}$y)³= ($\dfrac{1}{2}$x²)³ + 3.($\dfrac{1}{2}$x²)². $\dfrac{1}{4}$y + 3.$\dfrac{1}{2}$x².($\dfrac{1}{4}$)²+ ($\dfrac{1}{4}$)³

C4:

(3x²-2y)³= (3x²)³-3.(3x²)².2y+ 3.3x².(2y)²- (2y)³

=27$x^{6}$- 54$x^{4}$y+ 36x²y²-8y³

C5:

($\dfrac{2}{3}$x²-$\dfrac{1}{2}$y)³= ($\dfrac{2}{3}$x²)³- 3.($\dfrac{2}{3}$x²)². $\dfrac{1}{2}$y+ 3.$\dfrac{2}{3}$x². ($\dfrac{1}{2}$y)² + ($\dfrac{1}{2}$y)³

=$\dfrac{8}{27}$$x^{6}$- $\dfrac{2}{3}$$x^{4}$y + $\dfrac{1}{2}$x²y²+ $\dfrac{1}{8}$y³