Em cần bài nào em ha?
2:
a:=>2x^2-6x+5x-15=0
=>(x-3)(2x+5)=0
=>x=3 hoặc x=-5/2
b: \(\Leftrightarrow\left\{{}\begin{matrix}\dfrac{x}{1-x}=1\\\dfrac{y}{y+1}=2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1-x\\2y+2=y\end{matrix}\right.\)
=>x=1/2 và y=-2
`C1:`
`a)A=2\sqrt{40\sqrt{12}}-2\sqrt{\sqrt{75}}-3\sqrt{5\sqrt{48}}`
`A=2\sqrt{80\sqrt{3}}-2\sqrt{5\sqrt{3}}-3\sqrt{20\sqrt{3}}`
`A=8\sqrt{5\sqrt{3}}-2\sqrt{5\sqrt{3}}-6\sqrt{5\sqrt{3}}`
`A=0`
`b)` Với `x >= 0,x ne 9` có:
`Q=[2\sqrt{x}]/[\sqrt{x}-3]-[x+6\sqrt{x}+9]/[x-9]-\sqrt{x}/[\sqrt{x}+3]`
`Q=[2\sqrt{x}(\sqrt{x}+3)-x-6\sqrt{x}-9-\sqrt{x}(\sqrt{x}-3)]/[(\sqrt{x}-3)(\sqrt{x}+3)]`
`Q=[2x+6\sqrt{x}-x-6\sqrt{x}-9-x+3\sqrt{x}]/[(\sqrt{x}-3)(\sqrt{x}+3)]`
`Q=[3\sqrt{x}-9]/[(\sqrt{x}-3)(\sqrt{x}+3)]`
`Q=3/[\sqrt{x}+3]`
