# Can someone help me with my daughter's homework? **URL:** \ **Category:** Factual Questions\ **Created:** [January 30, 2015, 1:12am UTC](https://boards.straightdope.com/t/can-someone-help-me-with-my-daughters-homework/711294 "2015-01-30T01:12:17Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![shellofmyformerself](https://avatars.discourse-cdn.com/v4/letter/s/5f8ce5/32.png) [@shellofmyformerself](https://boards.straightdope.com/u/shellofmyformerself)\ **Post date:** [January 30, 2015, 1:12am UTC](https://boards.straightdope.com/t/can-someone-help-me-with-my-daughters-homework/711294/1 "2015-01-30T01:12:17Z")
Yes, it is embarrassing…my daughter needs help with her Algebra I homework and I can’t help. I don’t remember how to do it (I wasn’t that great at math myself) and I can’t decipher the example problems in her book. I don’t want to give her the answer, I just need a reminder how to work the problems so I can work with her. They are working on exponential equations. One of the example problems is: Simplify (81^1/4)^-2 (81 to the one-fourth, to the negative 2) They are supposed to write it in radical form? Can someone explain this at the most basic level so I can help her? ---
**Author:** ![excavating\_for\_a\_mind](https://avatars.discourse-cdn.com/v4/letter/e/e8c25b/32.png) [@excavating\_for\_a\_mind](https://boards.straightdope.com/u/excavating_for_a_mind)\ **Post date:** [January 30, 2015, 1:32am UTC](https://boards.straightdope.com/t/can-someone-help-me-with-my-daughters-homework/711294/2 "2015-01-30T01:32:24Z")
You multiply exponents. (81^1/4)^-2 = 81^-1/2 A negative exponent is the inverse of the positive exponent 81^-1/2 = 1/81^1/2 Fractional exponents are roots 1/81^1/2 = 1/sqrt(81) use the radical sign for sqrt or, 1/9 ---
**Author:** ![shellofmyformerself](https://avatars.discourse-cdn.com/v4/letter/s/5f8ce5/32.png) [@shellofmyformerself](https://boards.straightdope.com/u/shellofmyformerself)\ **Post date:** [January 30, 2015, 1:41am UTC](https://boards.straightdope.com/t/can-someone-help-me-with-my-daughters-homework/711294/3 "2015-01-30T01:41:08Z")
Thanks! I think I can follow that… ---
**Author:** ![CraterLayer](https://avatars.discourse-cdn.com/v4/letter/c/87869e/32.png) [@CraterLayer](https://boards.straightdope.com/u/CraterLayer)\ **Post date:** [January 30, 2015, 1:42am UTC](https://boards.straightdope.com/t/can-someone-help-me-with-my-daughters-homework/711294/4 "2015-01-30T01:42:57Z")
81^1/4 means the cube root of 81, which is 3 ( 3x3x3x3 = 81). 3^-2 means 1/(3^2), or 1/9 ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [January 30, 2015, 2:06am UTC](https://boards.straightdope.com/t/can-someone-help-me-with-my-daughters-homework/711294/5 "2015-01-30T02:06:45Z")
> [@CraterLayer](#): > > 81^1/4 means the cube root of 81, which is 3 ( 3x3x3x3 = 81). What you described is the fourth root, not cube root. ---
**Author:** ![CraterLayer](https://avatars.discourse-cdn.com/v4/letter/c/87869e/32.png) [@CraterLayer](https://boards.straightdope.com/u/CraterLayer)\ **Post date:** [January 30, 2015, 2:16am UTC](https://boards.straightdope.com/t/can-someone-help-me-with-my-daughters-homework/711294/6 "2015-01-30T02:16:41Z")
Sorry, been a long time. How can 1/9 be represented as a radical? Would the square rot of 1/81 be correct or is there a fancier way? ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [January 30, 2015, 2:41am UTC](https://boards.straightdope.com/t/can-someone-help-me-with-my-daughters-homework/711294/7 "2015-01-30T02:41:21Z")
> [@CraterLayer](#): > > Sorry, been a long time. How can 1/9 be represented as a radical? Would the square rot of 1/81 be correct or is there a fancier way? You got the answer right, you just called it the wrong thing. “Cube root” is x^(-1/3), not x^(-1/4). Thinks of x^2 is “x squared” and x^3 is “x cubed”. ---
**Author:** ![excavating\_for\_a\_mind](https://avatars.discourse-cdn.com/v4/letter/e/e8c25b/32.png) [@excavating\_for\_a\_mind](https://boards.straightdope.com/u/excavating_for_a_mind)\ **Post date:** [January 30, 2015, 3:30am UTC](https://boards.straightdope.com/t/can-someone-help-me-with-my-daughters-homework/711294/8 "2015-01-30T03:30:07Z")
> [@shellofmyformerself](#): > > Thanks! I think I can follow that… Great! But, the real question is can your daughter follow it? That is the whole point of the exercise. ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [January 30, 2015, 5:51am UTC](https://boards.straightdope.com/t/can-someone-help-me-with-my-daughters-homework/711294/9 "2015-01-30T05:51:51Z")
> [@CraterLayer](#): > > 81^1/4 means the cube root of 81, which is 3 ( 3x3x3x3 = 81). Pay no attention to that man behind that curtain. 🙂 ---
**Author:** ![shellofmyformerself](https://avatars.discourse-cdn.com/v4/letter/s/5f8ce5/32.png) [@shellofmyformerself](https://boards.straightdope.com/u/shellofmyformerself)\ **Post date:** [January 30, 2015, 1:35pm UTC](https://boards.straightdope.com/t/can-someone-help-me-with-my-daughters-homework/711294/10 "2015-01-30T13:35:24Z")
> [@excavating\_for\_a\_mind](#): > > Great! But, the real question is can your daughter follow it? That is the whole point of the exercise. I agree, but if I can’t understand the reply, I can’t explain it to my daughter. 🙂 I did understand and was able to help her, but then we got stuck on other problems. She’s going to ask her teacher to go over it again with her today in class. Thanks everyone for the explanations!