Trình bày lời giải:
`a)`
`6x(x-2)+3x=6x^2+10`
`<=>6x^2-12x+3x=6x^2+10`
`<=>6x^2-9x=6x^2+10`
`<=>6x^2-9x-6x^2-10=0`
`<=>-9x-10=0`
`<=>-9x=10`
`<=>x=-10/9`
Vậy `x=-10/9`
`b)`
`(2x+1)(x-4)=(2x+1)^2`
`<=>(2x+1)(x-4)-(2x+1)^2=0`
`<=>(2x+1)(x-4)-(2x+1)(2x+1)=0`
`<=>(2x+1)(x-4-2x-1)=0`
`<=>(2x+1)(-x-5)=0`
`<=>[(2x+1=0),(-x-5=0):}`
`<=>[(2x=-1),(-x=5):}`
`<=>[(x=-1/2),(x=-5):}`
Vậy `x=-1/2;x=-5`