Câu 9:
a: ĐKXĐ: a>=0; a<>1
\(Q=\left(1+\sqrt{a}\right)\left(1-\sqrt{a}\right)=1-a\)
b: Để Q>0 thì 1-a>0
=>a<1
=>0<a<1
a. ĐKXĐ: \(a\ge0;a\ne1\)
\(Q=\left(1+\dfrac{\sqrt{a}\left(\sqrt{a}+1\right)}{\sqrt{a}+1}\right)\left(1+\dfrac{\sqrt{a}\left(\sqrt{a}-1\right)}{1-\sqrt{a}}\right)\)
\(=\left(1+\sqrt{a}\right)\left(1-\sqrt{a}\right)=1-a\)
b.
\(Q>0\Rightarrow1-a>0\Rightarrow a< 1\)
Kết hợp ĐKXĐ \(\Rightarrow0\le a< 1\)