4x2 -9y2-(2x+3y) 因式分解因式分解 第一题：4x2 -9y2-(2x+3y)第二题：x3-x2-xy-y2-y3第三题：x3-2x2+2x-1第四题：a2-b2+b-1/4第五题：x2+2xy+y2+7x+7y-18

第一题：4x2 -9y2-(2x+3y)
=(2x+3y)(2x-3y)-(2x+3y)
=(2x+3y)(2x-3y-1)
第二题：x3-x2-xy-y2-y3
=x³-y³-(x²+xy+y²)
=(x²+xy+y²)(x-y-1)
第三题：x3-2x2+2x-1
=x³-1+2x(x-1)
=(x-1)(x²+3x+1)
第四题：a2-b2+b-1/4
=a²-(b²-b+1/4)
=(a+b-1/2)(a-b+1/2)
第五题：x2+2xy+y2+7x+7y-18
=(x+y)²+7(x+y)-18
=(x+y+9)(x+y-2)