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ACT Mathematics Videos 164 videos
ACT Math: Coordinate Geometry Drill 1, Problem 1. Which inequality is expressed by the number line?
ACT Math: Intermediate Algebra: Drill 3, Problem 1. Find the fifth number in the series.
ACT Math Intermediate Algebra Drill 2, Problem 2. How else can the expression be written?
ACT Math 6.1 Elementary Algebra 224 Views
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Description:
ACT Math: Elementary Algebra Drill 6, Problem 1. Which of the following is not a factor of x 3 – x?
Transcript
- 00:02
And here's another shmoop du jour... Which of the following is not a factor of
- 00:06
x cubed minus x?
- 00:08
And here are the potential answers...
- 00:14
Okay can we factor?
- 00:15
Here, the common element on both sides of the minus sign is x.
Full Transcript
- 00:19
If we pull out that x...
- 00:20
...we get x times the quantity x squared minus 1.
- 00:24
But now we have x squared minus 1... it's a magic number we should recognize.
- 00:29
X squared minus 1 is a factorable beast...
- 00:33
...in quantity x plus 1 times quantity x minus 1.
- 00:38
So the factors are x... then quantity x plus 1... then quantity x minus 1.
- 00:43
If we look down our answers list, the only factor left that ISN'T an element of this
- 00:47
equation is x squared plus 1...
- 00:49
... so the answer is... E.
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