解方程x²-5x+2=0

解方程x²-5x+2=0
解方程x²-5x+2=0

解方程x²-5x+2=0
x²-5x+2=0
x^2-5x=-2
x^2-5x+25/4=-2+25/4
x^2-5x+25/4=17/4
(x-5/2)^2=17/4
x=(5+根号17)/2,x=(5-根号17)/2

x²-5x+2=0
x²-5x+25/4-17/4=0
(x-5/2)²=17/4
x-5/2=±√17/2
x = 5/2±√17/2
x = (5±√17)/2