7x²=9+x
so
for
0=ax²+bx+c
[tex]x=\frac{-b+/-\sqrt{b^2-4ac}}{2a}[/tex]
so
7x²=9+x
mins 9 from both sides and minus x
7x²-1x-9=0
a=7
b=-1
c=-9
[tex]x=\frac{-(-1)+/-\sqrt{(-1)^2-4(7)(-9)}}{2(7)}[/tex]
[tex]x=\frac{1+/-\sqrt{(-1)^2+4(7)(9)}}{2(7)}[/tex]
so the 4th one
