Explanation for Question 11 From the Math (No Calc) Section on the 2018 May Sat
Question 11 says the system of equations above is graft in the X, 2 Y plane. The graph of the equations intersect at a point X, 3 Y where X is greater than zero. 4 And why is it greater than zero? What is the Y coordinate of this 5 point of intersection? So we're going to start by taking these two equations at 6 the top and setting them equal to each other. 7 We're going to use that to find our X value and then plug that 8 in to find the value of Y at the point of intersection. 9 So since both of these equations are equal to Y I'm just going to 10 set them equal to each other. X squared is equal to two X 11 plus three. And then when I move that all onto one side, 12 it becomes X squared plus negative two X plus 13 negative three is equal to zero. 14 And that factors into X minus three X 15 plus one. So we know that X is equal to three 16 and X is equal to negative one. Now it tells us in the problem 17 that X is greater than zero, which means that when we plugged back in 18 our X value, we're going to use the positive value three. 19 So now let's do that. Y is equal to X squared. 20 Well, three squared is just equal to nine. So we know that Y is 21 equal to nine. And so the correct answer here is answer 22 D no.