Question

Tính:

a) \(2\sqrt{a^2}\left(a\ge0\right)\)

b) \(\sqrt{3a^2}\left(a< 0\right)\)

c) \(5\sqrt{a^4}\left(a< 0\right)\)

d) \(\dfrac{1}{3}\sqrt{c^6}\left(c< 0\right)\)

Answer 1

a) \(2\sqrt{a^2}=2\left|a\right|=2a\) (vì \(a\ge0\))

b) \(\sqrt{3a^2}=\left|a\right|\sqrt{3}=-a\sqrt{3}\) (vì \(a< 0\))

c) \(5\sqrt{a^4}=5\sqrt{\left(a^2\right)^2}=5\left|a^2\right|=5a^2\)

d) \(\dfrac{1}{3}\sqrt{c^6}=\dfrac{1}{3}\sqrt{\left(c^3\right)^2}=\dfrac{1}{3}\left|c^3\right|=\dfrac{1}{3}\left(-c^3\right)=-\dfrac{1}{3}c^3\) (vì \(c< 0\Rightarrow c^3< 0\))

Answer 2

\(a)2\sqrt{a^2}=2.\left|a\right|=2a\) ( vì \(a\ge0\) )

\(b)\sqrt{3a^2}=\left|a\right|\sqrt{3}=-a\sqrt{3}\) ( vì \(a< 0\) )

\(c)5\sqrt{a^4}=5\sqrt{\left(a^2\right)^2}=5\left|a^2\right|=5a^2\)

\(d)\dfrac{1}{3}\sqrt{c^6}=\dfrac{1}{3}\sqrt{\left(c^3\right)^2}=\dfrac{1}{3}\left|c^3\right|=\dfrac{1}{3}\left(-c^3\right)\) ( vì \(c< 0\Rightarrow c^3< 0\) )

Chúc bn học tốt!