Explanation for Question 19 From the Math (Calc) Section on the Official Sat Practice Test 8
So question number 19 has described a graph for us. 2 They've described two parts of the graph, the range and the zeros. 3 So let's start by looking at the range, which I've highlighted here in blue. 4 It says that the range is real numbers less than or equal to four. 5 So if I'm thinking about range, I'm thinking about the Y axis. 6 And if my range has to be real numbers less than or equal to 7 four, then that means that I should not go above four on my Y 8 axis. I can only go four and below, 9 right? So here 1, 2, 3, 4, 10 we can see that the highest point on this graph is four. 11 And then it goes below, which is a reason to keep this answer, 12 right? Because we want less than below or equal to four. 13 So a is a possible answer. Now B also has a 14 maximum of four. 15 I don't go above four, but I do go less than four in my 16 range, which is again, my Y axis here. 17 Now C is not going to work, 18 right? Because I started negative four and I go up. 19 So I have values that are larger than four when I'm only supposed to 20 have values that are either four or smaller. So C doesn't work because the 21 range is no good and similar for D right. 22 I have a value way up here, which is much larger than four, 23 which I'm not allowed to have. So the question now of how we distinguish 24 between a and B is by looking at the zeros. 25 I need zeros at negative three in one, and zeros are where I crossed 26 the X axis, or I cross the X axis. 27 And now if I look at AIC, have a zero at 1, 2, 3, 28 negative three and one. So a is probably our right answer. 29 Right. But we can check B just in case B I have a negative 30 one in a positive three. So just to check, 31 we did want the negative for you. We wanted the positive one. 32 So our best answer is going to be a.