Explanation for Question 11 From the Math (No Calc) Section on the Official Sat Practice Test 8
So question number 11 is asking us, which of the following equations corresponds to 2 the graph that we're given. And so one thing we can think about here 3 are what are the zeros of our graph? 4 So I can see that we have a zero here at negative three, 5 right? We have a zero at two, and we have a zero, 6 zero. And so if I have a zero at negative three, 7 then one of my pieces in that equation must be an X plus three, 8 because when I solve for X like this, 9 it would give me an X equals negative three. Right? So one of my 10 pieces should be X plus three. I see that I have that in a, 11 I have that in B, but I don't have that in C or D. 12 And so now we can move on to this part here, 13 right? The two. 14 Now, if it's a positive two is my solution effects is equal to positive. 15 Two is subtract two from both sides. 16 And I can see that one of my pieces should be X minus two, 17 right? If it's an X minus two, 18 which I have in both of them. And so the question is, 19 should I use an X or should I use an X squared? 20 And this comes with a little bit of knowledge of knowing how graphs work. 21 Right? One thing that we can notice is that at this zero, 22 we go straight through and this year we go straight through, 23 but X equals zero. We actually bounce off. 24 Now, when you go straight through, you have an odd exponent. 25 So for example, with the X plus three, we can see that we have 26 an invisible exponent of one and one is odd, 27 but on two we bounce, right? And when you bounce off 28 of an axis, you want even exponent. 29 Now here we have an invisible one, right? And what is odd and what 30 is even two is going to be even, 31 and since we bounce off of zero and I needed even exponent, 32 our correct answer is going to be B.