因式分解：（1）3x^2+7x+2 (2)5x^2+13x-6=0 (3)6x^2+13x-15=0
问题描述：
因式分解：（1）3x^2+7x+2 (2)5x^2+13x-6=0 (3)6x^2+13x-15=0
答
1).=(3x+1)(x+2)
2).=(5x-2)(x+3)
3).=(6x-5)(x+3)
答
(1) 3x^2+7x+2=(3x+1)(x+2)
(2) 5x^2+13x-6=(5x-2)(x+3)
(3) 6x^2+13x-15=(6x-5)(x+3)
答
（1）3x^2+7x+2 =3x^2+6x+x+2=3x(x+2)+(x+2)=(x+2)(3x+1)(2)5x^2+13x-6=0 5x^2-2x+15x-6=0x(5x-2)+3(5x-2)=0(5x-2)(x+3)=0x=2/5,x=-3(3)6x^2+13x-15=06x^2+18x-5x-15=06x(x+3)-5(x+3)=0(x+3)(6x-5)=0x=-3,x=5/6
答
(1)(3x+1)(x+2)
(2)(5x-2)(x+3)=0
(3)(6x-5)(x+3)=0