Question

[Nhi Trần]

Tính hằng đẳng thức đáng nhớ:

a) (x + 4 )(x²- 4x + 16)

b) (x-3y)(x²+3xy+9y²)

c) (1/3x + 2y ) ( 1/9x²- 2/3xy + 4y²) 

d) (x²-1/3)(x⁴ + 1/3x² + 1/9)

TÍNH GIÚP EM VS Ạ. THANKS

Answer 1

[Thanh Ngân]

\(\left(x+4\right)\left(x^2-4x+16\right)\)

\(=x^3-4x^2+16x+4x^2-16x+64\)

\(=x^3+64\)

\(\left(x-3y\right)\left(x^2+3xy+9y^2\right)\)

\(=x^2+3x^2y+9xy^2-3x^2y-9xy^2-27y^3\)

\(=\)\(x^2-27y^3\)

\(\left(\frac{1}{3}x+2y\right)\left(\frac{1}{9}x^2-\frac{2}{3xy}+4y^2\right)\)

\(=\)\(\frac{x^3}{27}-\frac{2}{9xy}+\frac{4xy^2}{3}+\frac{2x^2y}{9}-\frac{4y}{3xy}+8y^3\)

làm nốt nha