解下列方程x²-3x+1=0,2x²+6=7,3x²-9x+2=0,6x²-7x

x^2-3x+1=0.
(x-3/2)^2-9/4+1=0.
(x-3/2)^2=5/4.
x-3/2=±√5/2.
x1=3/2+√5/2；
x2=3/3-√5/2.
2x^2+6x=7.
2x^2+6x-7=0
2(x+3/2)^2-9/2-7=0.
(x+3/2)^2=23/4.
x+3/2=±√23/2.
x1=-3/2+√23/2；
x2=-3/2-√23/2.
3x^2-9x+2=0.
3(x-3/2)^2-27/4+2=0.
3(x-3/2)^2=19/4.
(x-3/2)^2=19/12.
x-3/2=±√57/6.
x1=3/2+√57/6；
x2=3/2-√57/6.
6x^2-7x+1=0.
6(x-7/12)^2-49/24+1=0.
6(x-7/12)^2=25/24.
(x-7/12)^2=25/(24*6).
x-7/12=±5/12.
x1=7/12+5/12=1.
x2=7/12-5/12=1/6.
5x^2-19=9x,----> 5x^2-9x-19=0.
5(X-9/10)^2-(81/20)-19*20/20=0.
5(x-9/10)^2=461/20
(x-9/10)^2=461/100.
x-9/10=±√461/10.
x1=9/10+√461/10；
x2=9/10-√461/10.
4x^2-3x=52.--->4x^2-3x-52=0.
4(x-3/8)^2-9/16-52*16/16=0.
4(x-3/8)^2=841/16.
(x-3/8)^2=841/64.
x=3/8±29/8.
x1=3/8+29/8
x1=4；
x2=-13/4.
5x^2=4-2x ----> 5x^2+2x-4=0.
5(x+1/5)^2-1/5-20/5=0.
(x+1/5)^2=21/25.
x+1/5=±√21/5.
x1=-1/5+√21/5；
x2=-1/5-√21/5.
----玩-----.

运用求根公式即可求出

x^2-3x+1=0.
(x-3/2)^2-9/4+1=0.
(x-3/2)^2=5/4.
x-3/2=±√5/2.
x1=3/2+√5/2；
x2=3/3-√5/2.
2x^2+6x=7.
2x^2+6x-7=0
2(x+3/2)^2-9/2-7=0.
(x+3/2)^2=23/4.
x...

一元二次方程（ax^2+bx+c=0)求解，先判断b^2-4ac>=0
求根公式为：x=(-b+-√b^2-4ac)/2a