Question

Giúp tui hếc đựt k

Answer 1

`a)\sqrt{4-5x}=\sqrt{x-2}`       `ĐK: 4/5 <= x <= 2`

`<=>4-5x=x-2`

`<=>6x=6`

`<=>x=1` (t/m)

 

`b)\sqrt{7x-35}+2+\sqrt{4x-20}=\sqrt{3x-15}`    `ĐK: x >= 5`

`<=>\sqrt{7}\sqrt{x-5}+2+2\sqrt{x-5}=\sqrt{3}\sqrt{x-5}`

`<=>(\sqrt{3}-\sqrt{7}-2)\sqrt{x-5}=2`

`<=>\sqrt{x-5}=2/[\sqrt{3}-\sqrt{7}-2]` (Vô lí)

 

`c)\sqrt{6(x-3)^2}=36`   

`<=>\sqrt{6}|x-3|=36`

`<=>|x-3|=6\sqrt{6}`

`<=>x-3=+-6\sqrt{6}`

`<=>x=3+-6\sqrt{6}`