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SAT Math 4.6 Numbers and Operations 210 Views


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Description:

SAT Math 4.6 Numbers and Operations

Language:
English Language

Transcript

00:02

And here's an unshmoopy question you may find on an exams somewhere in life...

00:05

Both y and y to the one-third are negative integers.

00:09

Which of the following must also be a negative integer?

00:12

And here are the potential answers...

00:16

All right... we want to find the expression that gives us a negative integer given the

00:21

information provided in the problem.

00:30

In this case, choice A is the correct answer...

00:34

but let's first look at why the other options are incorrect.

00:37

Choice B is asking us to take the square root of a negative number, but that's impossible.

00:43

It's choice C's turn in the hot seat.

00:46

If y is negative, a negative number times a negative number will always be a positive number.

00:55

Choice D's up next.

00:57

y raised to the 2/3 power is the same thing as squaring y raised to the 1/3 power.

01:03

y raised to the 1/3 power is defined as being negative, so squaring it will make it positive.

01:09

Last up, choice E. It's important to know that taking the cubed

01:13

root of y is the same thing as raising y to the 1/3 power.

01:17

By multiplying y by y raised to the 1/3 power, we are multiplying 2 negatives, which gives

01:22

us a positive. Now back to the correct answer, choice A.

01:26

y raised to the 1/3 power is negative, and raising any negative number to an odd power

01:30

will yield another negative number. So bingo --

01:34

A it is.

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