Question 979144
you did it correct 

{{{ graph( 600, 600, -10, 10, -10, 10,x^2 + 6x + 8) }}}

check:

{{{x^2 + 6x + 8 = 0}}}.....if {{{x=-2}}}

{{{(-2)^2 + 6(-2) + 8 = 0}}}

{{{4 -12 + 8 = 0}}}

{{{12-12 = 0}}}

{{{0= 0}}}


{{{x^2 + 6x + 8 = 0}}}.....if {{{x=-4}}}

{{{(-4)^2 + 6(-4) + 8 = 0}}}

{{{16 -24 + 8 = 0}}}

{{{24-24 = 0}}}

{{{0= 0}}}