Question

rút gọn

 (3x-1).(2x+7)-(x+1).(6x-5)-(18x-12)

Answer 1

\(\left(3x-1\right)\left(2x+7\right)-\left(x+1\right)\left(6x-5\right)-\left(18x-12\right)=6x^2+21x-2x-7-6x^2+5x-6x+5-18x+12\)

\(=\left(6x^2-6x^2\right)+\left(21x-2x+5x-6x-18x\right)+\left(12+5-7\right)=10\)

Answer 2

\(=6x^2+19x-7-6x^2-x+5-18x+12\)

\(=\left(6x^2-6x^2\right)+\left(19x-18x\right)+\left(-7+5+12\right)-x\)

\(=x+10-x=10\)