Answer Choices
−3
−2
−1
0
Explanation for Question 16 From the Math (Calc) Section on the Official Sat Practice Test 3
Now number 16, we're given the graph of two parabolas, 2 right? And it tells us that they're shown above its F and G. 3 And we're asked which of the following for which of the following values of 4 X, this F of X plus G of X equals zero. 5 Right? So we're trying to find a point where the Y coordinates of both 6 graphs, when we add them together, they equal zero. 7 And so the best way to go about this, perhaps you can just look 8 at the graph and see it. Um, cause that means that F of X 9 and G of X, they must have the same number, right. 10 For example, to, um, but also be the opposite of each other. 11 Right? So one would be two, 12 one would be negative two or one would be three and one would be 13 negative three. And so maybe you can see that right off the bat, 14 but perhaps another good way to go about it is just to test each 15 answer choice. 16 Right? So let's look at negative three. This appears appears to be zero. 17 So negative three is 1, 2, 3. If we're here, 18 we see that it looks like G is zero. 19 So let's, let's do this at the next question to you at X looks 20 like G was zero. Um, but F was 21 negative one, right? 22 And negative one plus zero that's negative one, not zero. 23 So a didn't work out for us. If we try negative two that's right 24 here, we see that G of X appears to be positive to and F 25 of X appears to be negative two. So here we are, 26 here's our same number, but opposite. We add those together. 27 We get zero. And so B works here. 28 I mean, if you go on and you test negative one, you'll see, 29 uh, for your negative one, you also get negative one instead of zero. 30 And then at zero, it looks like you get a very negative number, 31 right? Two minus some big negative number. 32 And so the only answer choice where we add our two Y values together 33 that gives us zero is when X is equal to negative two.