Explanation for Question 28 From the Math (Calc) Section on the Official Sat Practice Test 6
Question 28 asks us two different points on a number line are both three 2 units from the point with coordinate negative for the solution to which the following 3 equations gives the coordinates of both points. 4 Okay. So to start this out, let's draw a picture. 5 We know that we have the coordinate negative four, 6 and we know that we're looking for two different points that are both three 7 units away from that negative four. 8 So moving three units in both directions, 9 we'll have negative four minus three is going to be equal to negative seven 10 and they're going to four plus three is going to be equal to negative 11 one. So we know that the two points that we're looking for are negative 12 seven and negative one. So one way to approach this, 13 if you're getting lost is to go through these systems of inequalities and solve 14 them and see if you got the solutions negative seven and negative one. 15 Now that is the longer way to do it. I'm going to talk you 16 through how to do it the short way by figuring out what this picture 17 represents. 18 So we can start by looking at this phrase and seeing that 19 it says that both points are three units from the point with coordinate negative 20 four. Now, when you look at this inequality, 21 X is basically standing for any point on this line here. 22 So anywhere on the number line, 23 and then it's going to be X plus or minus four, 24 we don't know which answer yet is going to be equal to three units 25 away. So the difference ...