\(1.4\\ a,=b\sqrt{a}\left(\sqrt{a}+1\right)+\left(\sqrt{a}+1\right)=\left(b\sqrt{a}+1\right)\left(\sqrt{a}+1\right)\\ b,=\left(\sqrt{x}-\sqrt{y}\right)\left(x+\sqrt{xy}+y\right)+\sqrt{xy}\left(\sqrt{x}-\sqrt{y}\right)\\ =\left(\sqrt{x}-\sqrt{y}\right)\left(x+2\sqrt{xy}+y\right)=\left(\sqrt{x}-\sqrt{y}\right)\left(\sqrt{x}+\sqrt{y}\right)^2\)
Bài 1.3
a: Ta có: \(\sqrt{2x+3}=\sqrt{2}+1\)
\(\Leftrightarrow2x+3=3+2\sqrt{2}\)
hay \(x=\sqrt{2}\)
b: Ta có: \(\sqrt{x+1}+\sqrt{5}=3\)
\(\Leftrightarrow x+1=14-6\sqrt{5}\)
hay \(x=13-6\sqrt{5}\)