Question 616984
To add to the other tutor's response:
... or you could factor it:
{{{12x^2+16x-28=0}}}
{{{4(3x^2+4x-7)=0}}}
{{{4(3x+7)(x-1)=0}}}
{{{3x+7 = 0}}} or {{{x-1=0}}}
{{{x = -7/3}}} or {{{x = 1}}}