# ACT Math 6.1 Elementary Algebra

ACT Math: Elementary Algebra Drill 6, Problem 1. Which of the following is not a factor of x^{3} – x?

ACT Math | Elementary Algebra |

ACT Mathematics | Elementary Algebra |

Elementary Algebra | Factoring polynomials Solve quadratic equations by factoring |

Foreign Language | Arabic Subtitled Chinese Subtitled Korean Subtitled Spanish Subtitled |

Language | English Language |

Polynomials | Factoring Polynomials |

Product Type | ACT Math |

### Transcript

If we pull out that x...

...we get x times the quantity x squared minus 1.

But now we have x squared minus 1... it's a magic number we should recognize.

X squared minus 1 is a factorable beast...

...in quantity x plus 1 times quantity x minus 1.

So the factors are x... then quantity x plus 1... then quantity x minus 1.

If we look down our answers list, the only factor left that ISN'T an element of this

equation is x squared plus 1...

... so the answer is... E.