ok so
we treat the group (x^2-6x) as u
quadratic formula
for au^2+bu+c=0
u=[tex] \frac{-b+/- \sqrt{b^2-4ac} }{2a} [/tex]
a=1
b=-11
c=-80
u=[tex] \frac{-(-11)+/- \sqrt{(-11)^2-4(1)(-80)} }{2(1)} [/tex]
u=[tex] \frac{11+/- \sqrt{121+320} }{2} [/tex]
u=[tex] \frac{11+/- \sqrt{441} }{2} [/tex]
u=[tex] \frac{11+/-21 }{2} [/tex]
u=[tex] \frac{32}{2} [/tex] or [tex] \frac{-10}{2} [/tex]
u=16 or -5
x^2-6x=16 or -5
solve each
x^2-6x=16
x^2-6x-16=0
(x-8)(x+2)=0
x=8 or -2
x^2-6x=-5
x^2-6x+5=0
(x-1)(x-5)=0
x=1 or 5
x=-2,1,5, or 8
