Answer
$(A + B)^{2} = A^2 + 2AB + B^2$
$(2x + 3)^2 = 4x^2 + 6x + 9$
Work Step by Step
When you square a term, you just multiply it by itself, therefore:
$(A + B)^{2} = (A + B)(A + B)$
Multiplying these by FOIL (first, outer, inner, last) yields
$A^2 + AB + AB + B^2$, which is equivalent to $A^2 + 2AB + B^2$
For part two, $A = 2x$ and $B = 3$, therefore this squared is:
$A^2 + 2AB + B^2$
$(2x)^2 + 2(2x)(3) + 3^2$
$4x^2 + 12x + 9$
