Question

Rút gọn: 

a/ \(\sqrt{72a^8\left(x^2-4x+4\right)}\) \(\left(a< 0;x< 2\right)\);

b/ \(\sqrt{40x^6\left(a^2+6x+9\right)}\left(x< 0;a>=-3\right)\)

Answer 1

\(\sqrt{72a^8\left(x^2-4x+4\right)}=\sqrt{72a^8\left(x-2\right)^2}=\sqrt{72}a^4|\left(x-2\right)|=\sqrt{72}a^4\left(2-x\right)\)

Answer 2

\(\sqrt{40x^6\left(a^2+6a+9\right)}=\sqrt{40x^6\left(x+3\right)^2}=\sqrt{40}|x^3\left(x+3\right)|=\sqrt{40}.\left(-x^3\right)\left(3-x\right)\)

\(=-\sqrt{40}x^3\left(3-x\right)\)

Answer 3

\(\sqrt{72a^8\left(x^2-4x+4\right)}\) \(=\sqrt{72a^8\left(x-2\right)^2}\)\(=\sqrt{72}a^4|\left(x-2\right)|=\sqrt{72}a^4\left(2-x\right)\)