Explanation for Question 28 From the Math (Calc) Section on the Official Sat Practice Test 10
Now for question number 28, we're given this equation of a parabola, 2 right? And it says, K is a positive integer, 3 which could only represent, um, 4 and which of the following could only represent the graph. 5 So K is a positive imagery. Let's just go ahead. 6 Let's pretend that K is two for example, 7 and this is just an example, right? So minus two. 8 So we noticed that it's written in a form. This equation is written in 9 such a form that we can find the X intercepts fairly easily. 10 Right? So if I set this first one, 11 this first set of parentheses equal to zero, 12 if you see that we would have an X intercept X equals negative three, 13 and we know that one, for sure, we should have an X intercept at 14 negative three. This one was kind of just, 15 you know, us playing around, trying to get to understand what these parameters that 16 they set, where I can add two to both sides. 17 And I have a seat that I have an exit positive too, 18 but the important part here is that this could be any positive number or 19 any, um, let's see here. 20 Yeah. Okay. It could be any positive number right here. 21 And so if I'm adding that positive number over, 22 because this minus sign, that means that no matter what, 23 this will always result in a positive X intercept, 24 can't say for sure what the number is, but we know it has to 25 be positive. So we're looking for a negative three and 26 a positive X intercept. Right. 27 And if we look at a sure enough, we have an X intercept a...