Explanation for Question 18 From the Math (No Calc) Section on the 2019 October Sat
Not for question number 18, we're given this expression or equation rather up 2 here and we're told to solve for X. 3 And so if I want to solve for X, what's really standing in my 4 way here is that square root. And so naturally what I really want to 5 do is square that square root so that I can get rid of the 6 root in my equation. So if I start by rewriting this and 7 I look at what I have here, and I decide what I really want 8 to square is this square root right here. 9 I need to get it on its own in order to square it and 10 to get it on its own. What I can do is move it from 11 the left side of the equation, where it is now over to the right 12 side of the equation to do that, 13 I can add two root X to both sides plus to root X plus 14 two root X. 15 Now these will cancel and I'll be left with X minus three is equal 16 to two root X. So now what I can do to get rid of 17 what's causing me really the problem here, which is that square root is I 18 can square both sides of the equation because when I square this side here, 19 I get rid of the radical. And when I square this side here, 20 really no issues are gonna pop up. It'll still be easy for me to 21 work with the X, with the equation. So two squared is four and the 22 square root of X squared is X. So this becomes four X. 23 And when I do X minus three squared, what I really need 24 to do here is foil, right? So I'll do X times X that's, 25 X squared, X minus three, 26 that's negative three X, another negative three...