Explanation for Question 9 From the Math (No Calc) Section on the 2017 April Sat
Question nine says this system of equations above is graft in the X Y 2 plane, which of the following is the Y coordinate of an intersection point of 3 the graphs of the two equations. So first I'm going to set these two 4 equations equal to each other, and I'm going to do that by changing this 5 bottom equation by subtracting one from both sides to make it X minus 6 one is equal to Y. Now both equations are set equal to Y so 7 I can set them equal to each other. So X squared plus negative six 8 X plus 11 is equal to X minus Y. 9 Then I'm going to move everything to the same side of the equation, 10 the left side, so that I can factor. So I'm going to subtract extra 11 moot sides and add one to both sides. 12 And that becomes X squared plus negative seven X plus 12 13 is equal to zero. Now I can factor this factors 14 into X minus three, whoops X 15 minus three times X minus four. 16 And after that, I know that the X values are equal to three 17 and four, but this one is to find the 18 Y value of an intersection point. 19 So I'm going to take this bottom equation down here and plug in three 20 and four. So let's start by just plugging in three, 21 three is equal to Y plus one, 22 if we subtract one from both sides, we get Y is equal to 23 two, and that is an answer choice. 24 That's answer choice C. And so we know that that's the correct.