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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
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
Full Transcript
- 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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