Explanation for Question 36 From the Math (Calc) Section on the Official Sat Practice Test 1
For question number 36, we're asked for what value of X is the function 2 H above undefined. And when you see the word undefined, 3 we should immediately think about dividing by zero divided by zero. 4 Because if you were to take your calculator and take any number and then 5 divide it by zero, you get a message that says air undefined. 6 So things are undefined when you're dividing by zero. 7 So our goal here is to take this denominator and find a spot where 8 it's equal to zero, right? So where is X minus five squared plus four 9 X minus five, plus four equal to zero. 10 And so we can think about factoring this out, 11 right where we have this piece right here, 12 functioning kind of like our X, right? 13 Usually we might've seen X squared plus four X plus four. 14 So our new X is like X minus five. 15 So what we can do to start to solve this is make Y equal 16 to X minus five. We're going to set a new variable so that this 17 doesn't look so funky anymore. So instead of X minus five squared, 18 I'll say Y squared because Y is equal to X minus five, 19 plus four Y again, cause Y is equal to X minus five. 20 Plus four is equal to zero and first I'll solve for Y. 21 And then once I know why I can solve for X, 22 right? So if I'm factoring this, I need to set up my double bubbles, 23 put a Y in the front. Cause I have Y squared and think about 24 what I can multiply together to give me positive four and what I can 25 add together to give me positive for the answer to that is t...