Question

Giải giúp mình nha ^^

1/ Tính:

a)\(\sqrt{48}-6\sqrt{\frac{1}{3}}+\frac{\sqrt{3}-3}{\sqrt{3}}\)

b)\(\frac{\sqrt{15}-\sqrt{5}}{\sqrt{3}-1}-\frac{5-2\sqrt{5}}{2\sqrt{5}-4}\)

2/ Tìm x:

a) \(\sqrt{4\left(1-x\right)^2}-12=0\)

b)\(\sqrt{4x^2-12x+9}=5\)

Answer 1

a) \(\sqrt{4\left(1-x\right)^2}-12=0\)

\(\sqrt{4\left(1-x\right)^2}=0+12\)

\(\sqrt{4\left(1-x\right)^2}=12\)

\(\left[\sqrt{4\left(1-x\right)^2}\right]^2=12^2\)

\(4-8x+4x^2=144\)

\(\Rightarrow\orbr{\begin{cases}x=7\\x=-5\end{cases}}\)

b) \(\sqrt{4x^2-12x+9}=5\)

\(\left(\sqrt{4x^2-12x+9}\right)^2=5^2\)

\(4x^2-12x+9=25\)

\(\Rightarrow\orbr{\begin{cases}x=4\\x=-1\end{cases}}\)

Answer 2

BÀI 1:

a)

\(A=4\sqrt{3}-2\sqrt{3}+1-\sqrt{3}\)

=>    \(A=\sqrt{3}+1\)

b)

\(B=\frac{\sqrt{5}\left(\sqrt{3}-1\right)}{\sqrt{3}-1}-\frac{\sqrt{5}\left(\sqrt{5}-2\right)}{2\left(\sqrt{5}-2\right)}\)

=>    \(B=\sqrt{5}-\frac{\sqrt{5}}{2}\)

=>    \(B=\frac{\sqrt{5}}{2}\)