first distibute ussing distributive property which is a(b+c)=ab+ac so
x(3x-8)=28
3x^2-8x=28
subtract 28 from both sides
3x^2-8x-28=0
if you can factor it then you get
xy=0 then x and/or y=0 so
to factor multiply first term and last term together so 3 times -28=-84
now find what 2 numbers will multiply to get -84 and add to get -8
factors of -84
-2,41
-3,28
-4,21
-6,14
-7,12
now add them together and find which ones add to 8 or -8
-2,41=39
-3,28=25
-4,21=17
-6,14=8
-7,12=5
the numbers are -14 and 6
group
3x^2+6x-14x-28
group
(3x^2+6x)+(-14x-28)
reverse distribute which is ab+ac=a(b+c)
(3x)(x+2)+(-14)(x+2)
reverse distribute again
(3x+(-14) times (x+2)
(3x-14)(x+2)=0
set each to zero
3x-14=0
x+2=0
3x-14=0
add 14 to both sides
3x=14
divide boh tisdes by 3
x=14/3
x+2=0
subtract 2 from both sides
x=-2
x=14/3 and -2
