`#tnvt`
`x^2-3x=0`
`<=>x(x-3)=0`
`<=>[(x=0),(x-3=0):}`
`<=>[(x=0),(x=3):}`
Vậy `x\in{0;3}`
`b)x(x+1)-2(x+1)=0`
`<=>(x+1)(x-2)=0`
`<=>[(x+1=0),(x-2=0):}`
`<=>[(x=-1),(x=2):}`
Vậy `x\in{-1;2}`
`c)4x^2-9=0`
`<=>(2x)^2-3^2=0`
`<=>(2x-3)(2x+3)=0`
`<=>[(2x-3=0),(2x+3=0):}`
`<=>[(x=3/2),(x=-3/2):}`
Vậy `x\in{3/2;-3/2}`
`d)2x^3-50x=0`
`<=>2x(x^2-25)=0`
`<=>2x(x-5)(x+5)=0`
`<=>[(2x=0),(x-5=0),(x+5=0):}`
`<=>[(x=0),(x=5),(x=-5):}`
Vậy `x\in{0;+-5}`
