4(x-3)的平方-9(x+3)的平方=0
[2(x-3)]的平方-[3(x+3)]的平方=0
[2(x-3)+3(x+3)]*[2(x-3)-3(x+3)]=0
(5x+3)(-x-15)=0
x=-3/5 x=-15