25-64x²=0

25-64x²=0

25-64x²=0
64x²=25
x²=25/64
x=±5/8

答案就是八分之五，x=0.625

25-64x²=0
=>64x^2=25
=>x^2=25/64
=>x=5/8 or x=-5/8
平方根有两个