分解因式(十字相乘法)

1.(X平方+x) (x平方+x-14)+24=0
令K=X平方+x
K(K-14)+24=0
K^2-14K+24=0
(K-2)(K-12)=0
K=2或K=12
即X^2+X=2或X^2+X=12
X^2+X-2=0或X^2+X-12=0
(X+2)(X-1)=0或(X+4)(X-3)=0
X=-2或X=1或X=-4或X=3

2.(2y+1)^2-8(2y+1)+15=0
[(2y+1)-3][(2y+1)-5]=0
(2y-2)(2y-4)=0
(y-1)(y-2)=0
y=1或y=2

1.(X平方+x) (x平方+x-14)+24=0
(x²+x)²-14(x²+x)+24=0
(x²+x-2)(x²+x-12)=0
(x+2)(x-1)(x+4)(x-3)=0
x1=-2,x2=1,x3=-4,x4=3

2.(2y+1)²-8(2y+1)+15=0
(2y+1-3)(2y+1-5)=0
y1=1,y2=2