[Video] Q8: For what value of n is |n − 1| + 1 equal to 0 ?

Explanation for Question 8 From the Math (Calc) Section on the Official Sat Practice Test 1

So number eight is asking us for what value of N is the absolute 2 value of N minus one, plus one equal to zero. 3 And so let's just for a second. Imagine that this whole thing here was 4 a new variable. Let's call it a, so we can say that a is 5 equal to the absolute value of N plus one. 6 Now, if I have a plus one is equal to zero, 7 right? Cause I want this whole thing, our value of our new variable 8 of a plus one to be equal to zero. 9 So I've written that as an equation here now, 10 for this to happen, I'd have to subtract one from both sides, 11 right? And that will tell us the a has to be equal to negative 12 one. That's the only possible way that we could get this entire equation 13 to be equal to zero as let's go back to what a is, 14 right? A is the absolute value of N plus one. 15 And I want that to be equal to negative one. And we can ask 16 ourselves, is that possible? And the answer is no, 17 right, because I have these absolute value symbols. 18 And that makes everything either zero, 19 zero or positive, right? So this value, 20 Hey, could be greater than or equal to zero. 21 And because negative one is a negative number, 22 it's not possible to get that with an absolute value. 23 And so that's why our correct answer would have to be D.