What is (2x - 3)²?

Squaring a binomial means multiplying it by itself: $(2x-3)(2x-3)=4x^2-6x-6x+9=4x^2-12x+9$, choice D. The middle term comes from the two cross products, $-6x$ twice. Choice A ($4x^2-9$) is the product $(2x-3)(2x+3)$, a difference of squares, not the square of a binomial. Choice C ($4x^2+9$) drops the middle term. Choice B ($2x^2-12x+9$) squares the $2$ incorrectly, getting $2x^2$ instead of $4x^2$. Remember that $(a-b)^2=a^2-2ab+b^2$, not $a^2-b^2$. Expanding with the pattern $(a-b)^2=a^2-2ab+b^2$ gives the same result as FOIL.