\(a^2+2ab^2+4b^4=\left(a+2b\right)^2-2ab^2=\left(a+2b-\sqrt{2ab^2}\right)\left(a+2b+\sqrt{2ab^2}\right)\)
Công thức 1: \(\left(a+b\right)^2=a^2+2ab+b^2\)
Công thức 2: \(a^2-b^2=\left(a-b\right)\left(a+b\right)\)
\(a^2+2ab^2+4b^4=\left(a^2+4ab^2+4b^4\right)-2ab^2=\left(a+2b^2\right)^2-2ab^2=\left(a+2b^2-\sqrt{2ab^2}\right)\left(a+2b^2+\sqrt{2ab^2}\right)\)
\(a^2+2ab^2+4b^4=\left(a+2b^2\right)^2\)