求几道一元二次方程的过程

(11)x^2+15x-54=0 答案：x1=-18 x2=3
(x+18)*(x-3)=0
(12)x^2+11x+18=0 答案：x1=-2 x2=-9
(x+2)*(x+9)=0
(13)x^2-9x+20=0 答案：x1=4 x2=5
(x-4)*(x-5)=0
(14)x^2+19x+90=0 答案：x1=-10 x2=-9
(x+10)*(x+9)=0
(15)x^2-25x+156=0 答案：x1=13 x2=12
(x-13)*(x-12)=0
(16)x^2-22x+57=0 答案：x1=3 x2=19
(x-3)*(x-19)=0
(17)x^2-5x-176=0 答案：x1=16 x2=-11
(x-16)*(x+11)=0
(18)x^2-26x+133=0 答案：x1=7 x2=19
(x-7)*(x-19)=0
(19)x^2+10x-11=0 答案：x1=-11 x2=1
(x+11)*(x-1)=0
(20)x^2-3x-304=0 答案：x1=-16 x2=19
(x+16)*(x-19)=0
一般情况下Ax^2+Bx+C=0可以化简成A（x+x1）*（x+x2）=0
且x1+x2=-(B/A) x1*x2=C/A
以后遇到带入就好了
懂吗

就是将通式Ax^2+Bx+C=0分解质因式，以AC的因式凑出B来。这种题目多做一些就会熟练了。祝好运