Đáp án:
`1)18x-2`
`2)42x-41`
`3)7/6x`
`4)-11x+10`
`5)x²-44/5x+45/2`
Giải thích các bước giải:
`1)(3x-1)(2x+7)-(x+1)(6x-5)`
`=6x²+21x-2x-7-(6x²-5x+6x-5)`
`=6x²+21x-2x-7-6x²+5x-6x+5`
`=(6x²-6x²)+(21x-2x+5x-6x)+(-7+5)`
`=18x-2`
`2)(3x-5)(7-5x)+(5x+2)(3x-2)-2`
`=21x-15x²-35+25x+15x²-10x+6x-4-2`
`=(-15x²+15x²)+(21x+25x-10x+6x)+(-35-4-2)`
`=42x-41`
`3)x(x-1/3)-1/2x(2x-3)`
`=x²-1/3x-x²+3/2x`
`=(x²-x²)+(-1/3x+3/2x)`
`=7/6x`
`4)6x²-(2x+5)(3x-2)`
`=6x²-(6x²-4x+15x-10)`
`=6x²-6x²+4x-15x+10`
`=(6x²-6x²)+(4x-15x)+10`
`=-11x+10`
`5)x(x+1/5)-(2x-5)(1/2+4)`
`=x²+1/5x-(2x-5). 9/2`
`=x²+1/5x-9x+45/2`
`=x²-44/5x+45/2`
