\(\left(x^2+\frac{2}{5}y\right)\left(x^2+\frac{2}{5}y\right)=x^4+\frac{4}{5}x^2y+\frac{4}{25}y\)
b\(\left(x^2-\frac{1}{3}\right)\left(x^4+\frac{1}{3}x^2+\frac{1}{9}\right)=\left(x^2-\frac{1}{3}\right)^3-x^2-\frac{1}{3}\)
Mà bạn có thể giải cụ thể giúp mình đc ko
\(\left(x^2+\frac{2}{5}y\right)\left(x^2+\frac{2}{5}y\right)=\left(x^2+\frac{2}{5}y\right)^2=\left(x^2\right)^2+2.x.\frac{2}{5}.y+\left(\frac{2}{5}y\right)^2=x^4+\frac{4}{5}xy+\frac{4}{5}y^2\)
\(\left(x^2-\frac{1}{3}\right)\left(x^4+\frac{1}{3}x^2+\frac{1}{9}\right)\)
\(=\left(x^2-\frac{1}{3}\right)\left[\left(x^2\right)^2+x^2.\frac{1}{3}+\left(\frac{1}{3}\right)^2\right]\)
\(=\left(x^2\right)^3-\left(\frac{1}{3}\right)^3\)