Explanation for Question 13 From the Math (No Calc) Section on the Official Sat Practice Test 9
Question 13 gives us this graph and it asks us the graph of the 2 function F and the X Y plane above is a parabola, 3 which of the following defines F. So we have these answer 4 choices right here, and the best way to solve this one, 5 I would say is process of elimination. So figuring out each bit of information 6 that we have about the prevalent one by one and going from there. 7 So we see that our vertex is at three one, 8 and vertex means the highest or lowest point of the parabola, 9 depending on if it's curbing up or down. So our vertex is 10 equal to three one, 11 and the convention for a parabola is, 12 is that the X coordinate of that will be reflected 13 inside of X minus something. 14 So here we know that our equation of the problem is going to be, 15 Y equals some coefficient times X minus three, 16 and my having it be X minus three, that's what places that at the 17 positive X is equal to three point on the graph. 18 That's going to be plus something. I mean, 19 we know that plus something is actually going to be equal to one because 20 the Y coordinate of the vertex is one. 21 So looking at our answer choices, we already can eliminate D 22 and B. And now we're left with a and C AMC. 23 The difference between them is this coefficient out in front. 24 There's a four for a, and there's an implied one for C. 25 And we're going to figure out which one is correct. We can just pick 26 any point and see which one reflects the answer or which one is 27 correct in that gi...