Explanation for Question 23 From the Math (Calc) Section on the 2020 October Sat
So question 23 is asking us, which of the following is equivalent to the 2 expression above four X does not equal route two. 3 And so this might be a little bit tough to read, but what we 4 can see here is that we have X squared minus two, 5 and then we actually have a factor of X squared minus two below. 6 So what this question is really asking us for is what is the other 7 factor of X squared minus two? 8 So X squared minus two, although not obvious because two is not a perfect 9 square is actually a, 10 um, a difference of squares, right? If I think about it that way, 11 and I asked myself, what is the square root of X squared? 12 We know that that's X and then for a difference of squares, 13 we always put a plus and a minus. And then we fill in the 14 last gap. And now this last gap has a two. 15 And even though the square root of two is not a beautiful, 16 perfect number, it's still a number and it can still be written as the 17 square root of T. Now, 18 here is already what I've written. 19 This is the part that's missing. This is the part that it's asking me 20 for. And so with that in mind, 21 knowing that the square root of two can be treated as kind of like 22 a perfect square, our correct answer is going to be de.