Đáp án + Giải thích các bước giải:
`a)\sqrt{2x-3}=7` `(x>=3/2)`
`⇒2x-3=49`
`⇔2x=52`
`⇔x=26`
`b)\sqrt{x^2-4x+4}=\sqrt{6-2\sqrt5}` `(x>=2)`
`⇔\sqrt{x^2-2.x.2+2^2}=\sqrt{5-2.\sqrt5.1+1}`
`⇔\sqrt{(x-2)^2}=\sqrt{(\sqrt5-1)^2}`
`⇒x-2=\sqrt5-1`
`⇔x=\sqrt5+1`
`c)\sqrt{3x+1}=\sqrt{4x-3}` `(x>=3/4)`
`⇒3x+1=4x-3`
`⇔-x=-4`
`⇒x=4`
`d)\sqrt{9x+18}-5\sqrt{x+2}+4/5\sqrt{25x+50}=6` `(x>=-2)`
`⇔\sqrt{9(x+2)}-5\sqrt{x+2}+4/5\sqrt{25(x+2)}=6`
`⇔3\sqrt{x+2}-5\sqrt{x+2}+4/5.5\sqrt{x+2}=6`
`⇔3\sqrt{x+2}-5\sqrt{x+2}+4\sqrt{x+2}=6`
`⇔2\sqrt{x+2}=6`
`⇔\sqrt{x+2}=3`
`⇒x+2=9`
`⇔x=7`
