Question

đưa thừa số ra ngoài dấu căn

a)\(0,1\sqrt{20000}\)

b)\(-0,05\sqrt{28800}\)

c)\(\sqrt{7.63a^2}\)

d)\(\sqrt{72a^2b^4}v\text{ới}a< 0\)

 

Answer 1

a/ \(0,1\sqrt{2.10000=0,1\sqrt{ }2.100^{ }2=0,1\cdot100\sqrt{ }2=10\sqrt{ }2}\) 

b/ \(-0,05\sqrt{28800}=-0,05\sqrt{288\cdot100=-0,05\cdot10\sqrt{ }288=6\sqrt{ }2}\) 

c/\(\sqrt{7\cdot63}a^2=\sqrt{7\cdot9\cdot7}a^2=21a^2\) 

 

Answer 2

\(\sqrt{72a^{ }2b\sqrt{ }4=\sqrt{ }6\cdot9\left|\right|ab^{ }2=-3\sqrt{ }6ab^{ }2}\)

Answer 3

\(\sqrt{72a^{ }2b^{ }4}=\sqrt{6.9}\left|ab^{ }2\right|=3\sqrt{6}-\left(ab^{ }2\right)=-3\sqrt{6}ab^2\) 

mk sữa lại câu d