(2x-1)(3x+5)-2(x+1)(4x+3)
=6x²+7x-5-2(4x²+7x+3)
=6x²+7x-5-8x²-14x-6
=-2x²-7x-11为什么？楼上做的是对滴，我把式子写错了。（负3y减1）（3分之2x加2y）3分之2x加2y这个是：(2x/3)+2y还是(2x+2y)/3?（3分之2）x(-3y-1)(2x/3+2y)=-1/3×(3y-1)(2x+6y)=-1/3×(6xy-2x+18y²-6y)=-2xy+2x/3-6y²+2y