Find the equation of a quadratic function whose graph contains the given points
(4,,,8)

so, we have a system of equations of 3 variables... so... let's do some elimination, let's eliminate "c"
first by using the 1st and 2nd equations
and then by using the 1st and 3rd equations

by simply multiplying the 1st equation in both cases by -1, so we end up with -c atop, which will cancel out the +c at the bottom



now, notice the 2nd resultant equation with two varibles.. ended up equals to 0... so... .might as well let's do some substitution there, to get "b" then



now, let's use those in the 1st of the original equations