4x²-x-9=0
x^2 -1/4 x=9/4 (二次项系数化为1)
(x^2-1/4 x+1/64) =1/64 +9/4 (配方)
(x-1/8)^2=145/64
x-1/8 = ±√145 /8
x1=(1+√145)/8
x2=(1-√145)/8
4x²-x-9=0
x^2 -1/4 x=9/4 (二次项系数化为1)
(x^2-1/4 x+1/64) =1/64 +9/4 (配方)
(x-1/8)^2=145/64
x-1/8 = ±√145 /8
x1=(1+√145)/8
x2=(1-√145)/8