(1)x²-8x+15=0
(x-3)(x-5)=0
x=3,x=5
(2)x²-3x+1=0
直接代求根公式
x=(3-√5)/2,x=(3+√5)/2
(3)2x²+3x+1=0
(2x+1)(x+1)=0
x=-1/2,x=-1
(4)x²+(√2)x-1=0
直接代求根公式
x=(-√2-√6)/2,x=(-√2+√6)/2
(5)x²+(k-1)x-k=0 (x为未知数,k>-1)
(x-1)(x+k)=0
x=1,x=-k
(6)(t+1)²-3/2(t+1)=1
2(t+1)²-3(t+1)-2=0
[2(t+1)+1][(t+1)-2]=0
(2t+3)(t-1)=0
t=-3/2,t=1