Question

[anhle3112]

giúp vs 

áp dụng 7 hằng đẳng thức đáng nhớ

    (1/3x + 2y)(1/9x^2 - 2/3xy + 4y^2)

cảm ơn mấy bn nhiều

Answer 1

[Phạm Thị Thùy Linh]

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

\(=\left(\frac{1}{3}x+2y\right)\left[\left(\frac{1}{3}x\right)^2-\frac{1}{3}x.2y+\left(2y\right)^2\right]\)

\(=\left(\frac{1}{3}x\right)^3+\left(2y\right)^3\)

\(=\frac{1}{27}x^3+8y^3\)

Answer 2

[ミ★๖ۣۜSεηαbĭ ๖ۣۜTĭʂт ๖ۣۜKεү ★彡]

3x4y2+3x3y2+3xy2+3y2=3x3y2(x+1)+3y2(x+1)3x4y2+3x3y2+3xy2+3y2=3x3y2(x+1)+3y2(x+1)

=(3x3y2+3y2)(x+1)=3y2(x3+1)(x+1)=(3x3y2+3y2)(x+1)=3y2(x3+1)(x+1)

=3y2(x+1)(x2−x+1)(x+1)=3y2(x2−x+1)(x+1)2

chúc bn hc tốt