Question 360384
9x squared -9x-28=0
{{{9x^2 -9x-28=0}}}
.
Find some multiple of 'a' and 'c' that
multiplies to (9)(-28) and combines to -9:
9*28
3*3*2*2*7
(-21)(12)
.
Rewrite the middle term:
{{{9x^2 -21x+12x -28=0}}}
Group terms:
{{{(9x^2-21x)+(12x-28)=0}}}
Factor:
{{{3x(3x-7)+4(3x-7)=0}}}
{{{(3x-7)(3x+4)=0}}}
x ={-4/3, 7/3}