`a)`
`(3y^2-y+1)(y-1)+y^2(4-3y)=5/2`
`<=> 3y^3-y^2+y-3y^2+y-1+4y^2-3y^3=5/2`
`<=> (3y^3-3y^3)+(4y^2-y^2-3y^2)+(y+y)=5/2+1`
`<=> 2y=7/2`
`<=> y=7/4`
Vậy `y=7/4`
`b)`
`2x^2+3(x-1)(x+1)=5x(x+1)`
`<=> 2x^2+3(x^2-1)=5x^2+5x`
`<=> 2x^2+3x^2-3-5x^2-5x=0`
`<=> -5x=3`
`<=> x=-3/5`
Vậy `x=-3/5`