Explanation for Question 19 From the Math (Calc) Section on the Official Sat Practice Test 10
Not for number 19, we're looking at this equation here. 2 Y is equal to negative negative X minus three squared. 3 Plus a, the first thing that I want you to recognize is that this 4 is a vertex form of a parabola. 5 This is a general type of form of a parabola, 6 and we can use it to find some really cool information. 7 And so the question says that in the question above a is a constant, 8 that simply means that a is a normal number. 9 And the a is also always going to be the same number. 10 For example, if a were two a would always be two, 11 but it can also be a decimal as well. It could be a decimal, 12 but the most important thing is that a is constant. 13 It doesn't change. And that says to the graph of this equation is a 14 parabola. Like I said, because this is the vertex form of a parabola. 15 And that says which of the following is true about the parabola. 16 So to do this question, we need to understand how to read vertex form. 17 So let me give you general vertex form. 18 So we can say that Y is equal to, 19 um, usually we put an a here out in front and that's okay that 20 there's an a here as well. Just know that there are two different AEs. 21 This is just a normal variable. 22 This one you'll consistently see is a X minus H squared 23 plus K. And so in this case, 24 which I'll point out again, the, a value that they give us is really 25 a question of, you know, what is K and the most important thing 26 here is the a, the H and the K, 27 because H comma K gives ...