(X+y)(-2X-2分之1y)
=-2x²-1/2xy-2xy+1/2y²
=-2x²-3/2xy+1/2y²
(2x+1)(x-1)(2x-3)
=(2x²+x-1)(2x-3)
=4x³-6x²+2x²-3x-2x+4
=4x³-4x²-5x+3;2X平方-2(X-3)(3X-5)-3(X-2)(X+1) 其中X=1最后一题了求求你2X²-2(X-3)(3X-5)-3(X-2)(X+1) =2X²-2(3X²-14X+15)-3(X²-X-2)=2X²-6X²+28X-30-3X²+3X+6=-7X²+31X-24