x²-x-3/4=03x²+6x-5=04x²-x-9=0

x²-x-3/4=03x²+6x-5=04x²-x-9=0
x²-x-3/4=0
3x²+6x-5=0
4x²-x-9=0

x²-x-3/4=03x²+6x-5=04x²-x-9=0
x²-x-3/4=0
x²-x+1/4=1
(x-1/2)²=1
x-1/2=±1
x=1/2±1
所以
x1=3/2
x2=-1/2
3x²+6x-5=0
3(x²+2x+1)=8
3(x+1)²=8
(x+1)²=8/3
x+1=±2√6/3
x=-1±2√6/3
所以
x1=-1+2√6/3
x2=-1-2√6/3
4x²-x=9
x²-x/4=9/4
x²-x/4+1/64=9/4+1/64
(x-1/8)²=145/64
x-1/8=±√145/8
x=1/8±√145/8
所以
x=(1-√145)/8
x=(1+√145)/8
祝学习进步