x^2+5x+25/4=1+25/4
(x+5/2)^2=29/4
x^2-6x+9=2
(x-3)^2=2
3x^2-6x+3=7
3(x-1)^2=7
(x-1)^2=7/3
x^2-9x=12
x^2-9x+81/4=12+81/4
(x-9/2)^2=129/4
我觉得这样你自己能接着做了吧.
x^2+5x+25/4=1+25/4
(x+5/2)^2=29/4
x^2-6x+9=2
(x-3)^2=2
3x^2-6x+3=7
3(x-1)^2=7
(x-1)^2=7/3
x^2-9x=12
x^2-9x+81/4=12+81/4
(x-9/2)^2=129/4
我觉得这样你自己能接着做了吧.