9y²-18y-4=0
9(y²-2y)-4=0
9(y²-2y+1)-9-4=0
9(y-1)²=13
y-1=±√13/3
y=1+√13/3 or y=1-√13/3
解答:
9y^2-18y-4=0,所以:9(y^2-2y+1)=13
所以:(y-1)^2=13/9
所以:y-1=(根号13)/3
阿姨:y=1+(根号13)/3或y=1-(根号13)/3
y²-2y=4/9
y²-2y+1=4/9+1
(y-1)²=13/9
y-1=±√13/3
y=(3-√13)/3,y=(3+√13)/3
直接用公式法做啊……
y=(18±6√13)/18
=(3±√13)/3
(9y+2)(y-2)=0
y1=-9分之2,y2=2
9y2-18y-4=0
y2-2y-4/9=0
(y-1)^2-4/9-1=0
(y-1)^2=13/9
y=(±√13)/3+1