2（n-1/2）²-1=0 => (n-1/2)²=1/2
x²+2x-2=0 => (x+1)²-1-2=0 => (x+1)²=3
a²-5a-2=0 => (a-5/2)²-25/4-2=0 => (a-5/2)²=33/4
x²-3/4x=0 => (x-3/8)²-9/64=0 => (x-3/8)²=9/64
因为没法输入根号，所以后续的解题步骤需要你自己写了。
