(ax+b)(cx+d)=acx^2+(cb+ad)x+bd
a b cb
c d ad
———————————
ac. bd cb+ad
3x^2+8x+5=(x+1)(3x+5)
1 1 3
3 5 5
———————————
3 5 8
(ax+b)(cx+d)=acx^2+(cb+ad)x+bd
a b cb
c d ad
———————————
ac. bd cb+ad
3x^2+8x+5=(x+1)(3x+5)
1 1 3
3 5 5
———————————
3 5 8