Explanation for Question 15 From the Math (No Calc) Section on the Official Sat Practice Test 9
Question 15 asks us what is the set of all solutions to the equation? 2 The square root of X plus two is equal to negative X. 3 So the solution is going to be, it's essentially asking us for what range 4 of X values can we plug them in and make this equation true? 5 So we've got the square root of X plus two is equal to negative 6 X. And I think that the easiest way to solve this one is through 7 a guess and check. An important thing to note here is that these curved 8 brackets indicate that this is the domain. 9 So quick answer choice a is saying that all the numbers between negative one 10 and to fulfill this system of equations, 11 or excuse me, fulfills this equation. So it's saying that if we plug in 12 negative 1, 0, 1 or two, 13 those should all be correct. Now, 14 B and C are saying just the point negative one would work or just 15 the 0.2 would work. 16 So let's plug them in one by one and see what we get. 17 So we see that let's try negative one first. 18 So we've got negative one, plus two is equal to negative 19 one, and we want to see if that's true. So we've got the square 20 root of one is equal to negative one. 21 That is not true. So we can cross out both a and B because 22 negative one is not a valid point. Now we're also looking at two let's 23 plug in two plus two is equal to negative 24 two. It's got the square root of four is equal to negative two and 25 we've have two is equal to negative two. 26 That's not true either. So we can come to D there are no ...