Set 6: Quadratic Equations (Advanced)

Choice C is correct. Choice C is the correct answer. This expression fits the Difference of Squares pattern: $a^2 - b^2 = (a - b)(a + b)$. 1. Identify $a$ and $b$: $x^2$ is $(x)^2$ and $25$ is $(5)^2$. 2. Apply the formula: $(x - 5)(x + 5)$. This is a crucial pattern to recognize instantly on the SAT. Choice A is incorrect because $(x-5)^2 = x^2 - 10 x + 25$, which has a middle term. Choice B is incorrect because $(x+5)^2 = x^2 + 10 x + 25$, which also has a middle term. Choice D is incorrect because expanding it gives $x^2 - 24 x - 25$.