Question

Answer 1

26: ĐKXĐ: x>=3

\(\sqrt{x-3}+\sqrt{9x-27}-\dfrac{1}{2}\cdot\sqrt{4x-12}=6\)

=>\(\sqrt{x-3}+3\sqrt{x-3}-\dfrac{1}{2}\cdot2\sqrt{x-3}=6\)

=>\(3\sqrt{x-3}=6\)

=>\(\sqrt{x-3}=2\)

=>x-3=4

=>x=4+3=7(nhận)

28: ĐKXĐ: x>=-3

\(\sqrt{16x+48}-7\sqrt{x+3}+\dfrac{3}{4}\sqrt{4x+12}=-6\)

=>\(4\sqrt{x+3}-7\sqrt{x+3}+\dfrac{3}{4}\cdot2\sqrt{x+3}=-6\)

=>\(-\dfrac{3}{2}\sqrt{x+3}=-6\)

=>\(\sqrt{x+3}=6:\dfrac{3}{2}=6\cdot\dfrac{2}{3}=4\)

=>x+3=16

=>x=16-3=13(nhận)

30: ĐKXĐ: x>=3

\(\sqrt{16x-48}-8\sqrt{4x-12}+\dfrac{2}{3}\sqrt{9x-27}=-20\)

=>\(4\sqrt{x-3}-8\cdot2\sqrt{x-3}+\dfrac{2}{3}\cdot3\sqrt{x-3}=-20\)

=>\(4\sqrt{x-3}-16\sqrt{x-3}+2\sqrt{x-3}=-20\)

=>\(-10\sqrt{x-3}=-20\)

=>\(\sqrt{x-3}=2\)

=>x-3=4

=>x=4+3=7(nhận)