\(a,\dfrac{a\sqrt{a}-8+2a-4\sqrt{a}}{a-4}\left(dk:a\ne4\right)\)
\(=\dfrac{a\sqrt{a}-4\sqrt{a}-8+2a}{a-4}\)
\(=\dfrac{\sqrt{a}\left(a-4\right)+2\left(a-4\right)}{a-4}\)
\(=\dfrac{\left(a-4\right)\left(\sqrt{a}+2\right)}{a-4}\)
\(=\sqrt{a}+2\)
\(b,\dfrac{12\sqrt{6}}{\sqrt{7+2\sqrt{6}}-\sqrt{7-2\sqrt{6}}}\\ =\dfrac{12\sqrt{6}}{\sqrt{\left(\sqrt{6}+1\right)^2}-\sqrt{\left(\sqrt{6}-1\right)^2}}\\ =\dfrac{12\sqrt{6}}{\left|\sqrt{6}+1\right|-\left|\sqrt{6}-1\right|}\\ =\dfrac{12\sqrt{6}}{\sqrt{6}+1-\sqrt{6}+1}\\ =\dfrac{12\sqrt{6}}{2}\\ =6\sqrt{6}\)
Đúng 1
Bình luận (0)
