Mong các bạn giải nhanh giúp mik vs mai mik thi r
1.rút gọn : A=(2-\(\sqrt{2}\))(-5\(\sqrt{2}\))-(3\(\sqrt{2}\)-5)\(^2\)
2.a, rút gọn:B=(\(\dfrac{1}{\sqrt{a}-1}-\dfrac{1}{\sqrt{a}}\)):(\(\dfrac{\sqrt{a}+1}{\sqrt{a}-2}-\dfrac{\sqrt{a}+2}{\sqrt{a}-1}\))
b, Tìm a để B>0
3.-rút gọn C=(\(\dfrac{\sqrt{x}}{3+\sqrt{x}}+\dfrac{x+9}{9-x}\)):(\(\dfrac{3\sqrt{x}+1}{x-3\sqrt{x}}-\dfrac{1}{\sqrt{x}}\))
-Tìm x để C<-1
Câu 3:
\(C=\dfrac{3\sqrt{x}-x+x+9}{9-x}:\dfrac{3\sqrt{x}+1-\sqrt{x}+3}{\sqrt{x}\left(\sqrt{x}-3\right)}\)
\(=\dfrac{-3\left(\sqrt{x}+3\right)}{x-9}\cdot\dfrac{\sqrt{x}\left(\sqrt{x}-3\right)}{2\sqrt{x}+4}\)
\(=\dfrac{-3\sqrt{x}}{2\sqrt{x}+4}\)
Để C<-1 thì C+1<0
=>-3 căn x+2 căn x+4<0
=>-căn x<-4
=>x>16
