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CAHSEE Math 3.1 Algebra and Functions 222 Views
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Description:
Algebra and Functions: Drill Set 3, Problem 1. Evaluate the expression.
Transcript
- 00:03
And here's your shmoop du jour.
- 00:06
Evaluate the expression 3x3 - 4y-2 for x = 3 and y = 2.
- 00:15
Here are the potential answers...
- 00:16
Before we spoil the ending, hit pause and try it yourself.
- 00:23
Can we plug in numbers? Yes we can.
Full Transcript
- 00:27
If we substitute 3 as x and 2 as y, we can
- 00:30
rewrite the equation as 3 times 3 cubed minus 4 times 2 to the negative second...
- 00:36
3 cubed is 27... and 3 times 27 is 81 and we're done with the first part
- 00:43
Now for the y's.
- 00:44
Don't forget that little negative sign next to the 2 in the exponent.
- 00:49
Remember that negative exponents basically just mean "1 over"...
- 00:53
...so we can move the y squared into the denominator...
- 00:55
...and rewrite that second part as 4 over 2 squared. 2 squared is 4. 4 over 4 is 1.
- 01:02
We subtract one from 81 and we get 80. Answer: D
- 01:06
Plugging has never been more fun.
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