Question

分解因式：“1. x3-11x+20 2.x2-y2+5x+3y+4 3. 2x3-13x2+3

这是分解因式！！那里面是平方哦！请各位帅哥美M帮忙！！

Answer 1

解： x^3-11x+20 =x^3+(4x^2-4x^2)+(5x-16x)+20 =(x^3-4x^2+5x)+(4x^2-16x+20) =x(x^2-4x+5)+4(x^2-4x+5) =(x+4)(x^2-4x+5) x^2-y^2+5x+3y+4 =(x^2+5x)-(y^2-3y)+4 =(x^2+5x+6.25)-6.25-(y^2-3y+2.25)+2.25+4 =(x+2.5)^2-(y-1.5)^2-4+4 =(x+2.5)^2-(y-1.5)^2 =[(x+2.5)+(y-1.5)][(x+2.5)-(y-1.5)] =(x+y+1)(x-y+4) 2x^3-13x^2+3 =2x^3-12x^2-x^2-6x+6x+3 =(2x^3-12x^2-6x)-x^2+6x+3 =2x(x^2-6x-3)-(x^2-6x-3) =(2x-1)(x^2-6x-3)

麻烦采纳，谢谢!