化简 (2x+1)(x-1)(x+2) 和因式分解（2x-5)(x-3)+(3x-1)(5-2x)

显示全部楼层 · 2012-9-6 13:45:50

(2x+1)(x-1)(x+2)=(2x^2-x-1)(x+2)=2x^3+4x^2-x^2-2x-x-2=2x^3+3x^2-3x_2 （2x-5)(x-3)+(3x-1)(5-2x)=（2x-5)(x-3)-(3x-1)(2x-5)
(先化符号，有公因式提取）=（2x-5)(x-3-3x+1)=(2x-5)(-2x-2)
(括号内首项不能为负，所以负号放在因式的最前面）= -2(x+1)(2x-5)...

千问 · 2012-9-6 13:45:50

=（2x+1）(x2+x-2) =2x3+2x2-4x+x2+x-2 =2x3+3x2-3x-2;第二题=-2(2x-5)(x+1)...

化简 (2x+1)(x-1)(x+2) 和 因式分解（2x-5)(x-3)+(3x-1)(5-2x)

化简 (2x+1)(x-1)(x+2) 和因式分解（2x-5)(x-3)+(3x-1)(5-2x)