Nonlinear equations in one variable and systems of equations in two variables SAT question

Choice A is correct. It is given that y = x + 1 and y = x² + x. Setting the values for y equal to each other yields x + 1 = x² + x. Subtracting x from each side of this equation yields x² = 1. Therefore, x can equal 1 or –1. Of these, only –1 is given as a choice.

Choice B is incorrect. If x = 0, then x + 1 = 1, but x² + x = 0² + 0 = 0 ≠︀ 1. Choice C is incorrect. If x = 2, then x + 1 = 3, but x² + x = 2² + 2 = 6 ≠︀ 3. Choice D is incorrect. If x = 3, then x + 1 = 4, but x² + x = 3² + 3 = 12 ≠︀ 4.