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ACT Math Pre-Algebra: Drill 3, Problem 5. Simplify the expression.
ACT Math: Pre-Algebra Drill 4, Problem 5. If N is divisible by 2 and 3, then what is the remainder when N is divided by 6?
ACT Math 1.3 Pre-Algebra 542 Views
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Description:
ACT Math Pre-Algebra Drill 1, Problem 3. Can you find the product of two square roots?
Transcript
- 00:03
Here's an unshmoopy question you'll find on an exam somewhere in life...
- 00:06
Calculate the square root of 32 times the square root of 8.
- 00:10
And here are the potential answers...
- 00:15
OK, so this question is really all about factors
- 00:17
-- can we recognize and use them?
Full Transcript
- 00:19
We'll rarely be asked to calculate a square root that doesn't come out even on a test like this...
- 00:24
...so if we feel like we've been backed into that corner of actually having to calculate it...
- 00:28
...we may have messed up somewhere upstream.
- 00:30
That's not to say they won't ever throw a weird one in there,
- 00:33
but... it's just something to keep in mind.
- 00:35
So, in this case we have to think about the factors
- 00:37
of 32... 2 and 16 and 4 and 8.
- 00:42
First we have the square root of 32. What perfect squares go into 32 evenly?
- 00:47
Well, 4 does... but the bigger the better, in this case anyway...
- 00:51
16 times 2 equals 32, and 16 is 4 squared.
- 00:55
So we can rewrite this as the square root of 16 times 2, then we can pull out a 4 to
- 01:00
make it 4 square root of 2.
- 01:03
Next on the docket is the square root of 8. Now 4 is the best we can do.
- 01:07
The square root of 4 times 2 can be rewritten as 2 square root of 2.
- 01:12
When we multiply these two together, we get 4 times 2 is 8...
- 01:17
...and then square root of 2 times square root of 2 is... 2.
- 01:22
Multiply those two numbers together, and we're left with 16...
- 01:25
So the answer C.
- 01:25
As in, "Calculating villains."
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