Explanation for Question 14 From the Math (Calc) Section on the 2020 March Sat
So number 14 is telling us about a graph of the equation right here. 2 Y equals three X minus 12, 3 all over X plus two. And we want to know what is the Y 4 coordinate of the Y intercept of the graph, 5 right? And so you might be tempted to try to graph this graph. 6 Maybe you have a graphing calculator and you plug it in, 7 and that's not to say that that would work. You could possibly just plug 8 this into a graphing calculator that you have, but mathematically, 9 a really easy way to think about this is by thinking about what the 10 Y coordinate would be. Right? 11 If we're talking about a Y intercept, and this is something that gets tested 12 pretty often on the sat. Um, 13 but if we're talking about the Y intercept, 14 we have to be on this axis that I've outlined in red here. 15 And you can think about how, regardless of where your Y intercept is on 16 this axis. If I'm up here, if I'm down here, 17 no matter what my X coordinate will always be the same, 18 the X coordinate will always have to be zero because I'm not moving left 19 and right. Therefore I never leave the zero coordinate. 20 Now, if X is zero, I can plug zero in for both of these 21 Xs and simply solve for Y. 22 So that takes out any kind of calculator errors are trying to graph something 23 that's a little bit confusing here, and I can just really plug in zero. 24 And then from there, simplify zero plus two, 25 write in three times zero is zero. So it goes on the top. 26 Here is negative 12 and zero plus two is two. 27 So all I have now is Y equals negative 12 divided by two, 28 which is negative six, which is how we arrive at the answer of a.