1.计算:(x+7)(x﹣6)﹣(x﹣2)(x+1) =x2﹣6x+7x﹣42﹣x2﹣x+2x+2 =2x﹣40. 2.计算:(﹣2x2)3+(﹣3x3)2+(x2)2•x2 解:原式=﹣8x6+9x6+x6=2x6. 3.化简:(﹣x)2•(6x2)﹣2x•(﹣3x)3 解:原式=x2•6x2﹣2x•(﹣27x3)