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