Lets do FOIL (first,outside,inside,last)
(x + 3)(x + 4)
F.....multiply first terms in each set.....x * x = x^2
O...multiply outside terms in each set...x * 4 = 4x
I...multiply inside terms in each set....3 * x = 3x
L...multiply last terms in each set....3 * 4 = 12
put them together....x^2 + 4x + 3x + 12.....combine like terms....
x^2 + 7x + 12 <===
