Question

giải các phương trình :

a) \(\left(\sqrt{x}-7\right)\left(\sqrt{x-8}\right)=x+11\)

b) \(\left(\sqrt{x}+3\right)\left(\sqrt{x}-5\right)=x-17\)

c) \(1-\dfrac{2\sqrt{x}-5}{6}=\dfrac{3-\sqrt{x}}{4}\)

d) \(\left(\sqrt{x}+3\right)^2-x+3=0\)

Answer 1

\(a.\left(\sqrt{x}-7\right)\left(\sqrt{x}-8\right)=x+11\left(x\ge0\right)\)

\(\Leftrightarrow x-15\sqrt{x}+56=x+11\)

\(\Leftrightarrow15\sqrt{x}=45\)

\(\Leftrightarrow x=9\left(TM\right)\)

\(b.\left(\sqrt{x}+3\right)\left(\sqrt{x}-5\right)=x-17\left(x\ge0\right)\)

\(\Leftrightarrow x-2\sqrt{x}-15=x-17\)

\(\Leftrightarrow2\sqrt{x}=2\)

\(x=1\left(TM\right)\)

\(c.1-\dfrac{2\sqrt{x}-5}{6}=\dfrac{3-\sqrt{x}}{4}\left(x\ge0\right)\)

\(\Leftrightarrow\dfrac{2\left(2\sqrt{x}-5\right)+3\left(3-\sqrt{x}\right)}{12}=1\)

\(\Leftrightarrow x=169\left(TM\right)\)

\(d.\left(\sqrt{x}+3\right)^2-x+3=0\left(x\ge0\right)\)

\(\Leftrightarrow6\sqrt{x}=-12\left(vô-lý\right)\)

KL...............