Set 5: Quadratic Equations (Advanced)

Choice A is correct. Choice A is the correct answer. Use the FOIL method (First, Outer, Inner, Last) to expand the product of two binomials. 1. First: $x \times x = x^2$ 2. Outer: $x \times (-2) = -2 x$ 3. Inner: $5\times x = 5 x$ 4. Last: $5\times (-2) = -10$ Combine like terms: $x^2 + (-2 x + 5 x) - 10 = x^2 + 3 x - 10$. Choice B is incorrect because $5x - 2 x = +3 x$, not $-3 x$. Choice C is incorrect because it adds 5 and 2 instead of subtracting. Choice D is incorrect because $5\times (-2) = -10$, not +10.