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ACT Math: Pre-Algebra Drill 5, Problem 2. If a and b are prime numbers, how many factors does ab have?
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SAT Math 2.4 Numbers and Operations 384 Views
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Description:
SAT Math 2.4 Numbers and Operations
Transcript
- 00:02
Here’s your shmoop du jour, brought to you by negative integers.
- 00:06
They’re always preceded by a negative sign. Like…this one.
- 00:12
If x and y are negative integers, then x to the power of y can be which of the following?
- 00:17
And here are the potential answers...
- 00:21
So we have two mystery integers... both negative…
Full Transcript
- 00:25
…and we want to know what happens when we take one to the power of the other.
- 00:29
Remember, all it takes is ONE working example each of a positive real number, negative real
- 00:35
number or negative integer to do the trick… Let’s start with A – positive real number.
- 00:40
Is there an instance where this could happen?
- 00:43
Well…sure. Any time a negative number is squared, it becomes positive.
- 00:46
The negative sign in the exponent turns our number into a fraction.
- 00:49
So… if, for example, x was -1 and y was -2…
- 00:54
x to the power of y would become 1 over negative 1 squared. Which is just…1. So A works.
- 01:03
What about a negative real number?
- 01:05
Sure. If x is -1 and y is -3, the fraction we’d convert that to is 1 over -1 to the 3rd.
- 01:14
-1 to the 3rd is still negative one… since it gets reflected across the number line twice…
- 01:19
…and 1 over negative 1 is just negative 1…
- 01:22
…which is both a negative real number AND a negative integer…
- 01:25
…meaning that both B and C work as well.
- 01:28
And if A, B and C are all in the mix…
- 01:30
…then we’re going to have to go with E as our final answer.
- 01:33
We hope this video wasn’t a negative experience for you.
- 01:36
If so, watch it twice and it'll multiply into a positive.
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