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SAT Math 5.3 Algebra and Functions 210 Views
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Description:
SAT Math 5.3 Algebra and Functions
Transcript
- 00:03
Here’s your shmoop du jour, brought to you by positive integers.
- 00:06
Sometimes they’re so upbeat you just want to strangle them.
- 00:10
When a certain positive integer, n, is divided by 11, the remainder is 1.
- 00:14
What is the remainder when n + 10 is divided by 11?
- 00:19
And here are the potential answers…
Full Transcript
- 00:22
All right, so we’ve got some mystery number, and we know the remainder is 1 when you divide it by 11.
- 00:29
Now we want to tack on 10 more and do the same… and we need to determine the new remainder.
- 00:33
We need a quotient… we’ll call that k.
- 00:36
Let’s work in reverse. But be safe – check the rear view mirror first.
- 00:41
Multiplying both sides by 11 and then adding back the remainder gives us n = 11k + 1.
- 00:49
So now we’re looking for the remainder when n + 10 is divided by 11.
- 00:53
Adding 10 to both sides, n + 10 = 11k + 11.
- 00:58
Factoring out the 11, so n + 10 = 11(k + 1).
- 01:06
We want to figure out what the remainder is of (n + 10) divided by 11...
- 01:11
…so dividing both sides of the equation by 11 makes the left side exactly what we’re
- 01:14
looking for. When n + 10 is divided by 11 the quotient
- 01:18
is k + 1 and the remainder is 0. Looks like out answer is (A).
- 01:22
As in, “Auto repair.”