x²-5x-7=0
x²-5x=7
x²-5x+(5/2)²=7+(5/2)²
[x-(5/2)]²=53/4
x-(5/2)=±√(53/4)
x-(5/2)=±(√53)/2
x-(5/2)=(53)/2 或 x-(5/2)=-(√53)/2
x1=(5+√53)/2 ,x2=(5-√53)/2
x²-5x-7=0
x²-5x=7
x²-5x+(5/2)²=7+(5/2)²
[x-(5/2)]²=53/4
x-(5/2)=±√(53/4)
x-(5/2)=±(√53)/2
x-(5/2)=(53)/2 或 x-(5/2)=-(√53)/2
x1=(5+√53)/2 ,x2=(5-√53)/2