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Math problem with exponents and radicals
Posted by: Todd's keyboard
Date: October 25, 2021 09:58PM
The math teacher has been out with the flu. Normally an English teacher, I'm trying to help students with their math questions.

The 5th root of 8 squared times the 5th root of 8 cubed is?

My approach is to rewrite the first part as 8 to 2/5 and the second part as 8 to the 3/5. In that format, I can add the two fractional exponents to get 8 to the 5/5.

5/5 is 1, so 8 to the first power is 8.

The answer key given to the student is 4 to the 6/3.

To me, 6/3 simplifies to 2, so 4 squared (16).

Is the answer key correct? What am I missing?

thanks, Todd's keyboard
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Re: Math problem with exponents and radicals
Posted by: N-OS X-tasy!
Date: October 25, 2021 10:16PM
My answer is also eight.



It is what it is.
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Re: Math problem with exponents and radicals
Posted by: TheCaber
Date: October 25, 2021 10:31PM
Answer key is wrong. May not be the correct answer key for the text.

Your analysis and answer is correct.
You are missing a correct answer key.



=TC
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Re: Math problem with exponents and radicals
Posted by: Diana
Date: October 25, 2021 10:38PM
Todd,

You are correct. The answer key (as I’ve seen with other books) can be wrong, and in this case, I think it is incorrect. Email the math teacher; perhaps they will answer as to the HOW that this is being taught. The answer given makes no sense to me. Maybe the method will give some insight as to how it went wrong. Perhaps use it as a teaching moment?

I don’t know the age group of the students; in my experience, trying to teach a different method than they are used to can confuse them to the point where “math is too hard.” This is a barrier that STEM classes already face. This “trick” does need to be taught, as it makes dealing with exponentials and logs much easier in the long run.

Diana
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Re: Math problem with exponents and radicals
Posted by: freeradical
Date: October 25, 2021 10:51PM
I got 8 as an answer. I used the y^x button on my calculator to assist me. winking smiley
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Re: Math problem with exponents and radicals
Posted by: Todd's keyboard
Date: October 25, 2021 11:14PM
Folks,

Thanks for the feedback.

This is a high school for adults. The course are all self-paced, individual study. The adult students are either taking classes to get a high-school diploma for the first time or are upgrading courses they need to get into specific programs in colleges or universities.

thanks again^2,

T's kb
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Re: Math problem with exponents and radicals
Posted by: srf1957
Date: October 26, 2021 12:33AM
7.999999996
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Re: Math problem with exponents and radicals
Posted by: rich in distress
Date: October 26, 2021 12:36AM
I’m pretty sure it’s C)
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Re: Math problem with exponents and radicals
Posted by: pdq
Date: October 26, 2021 07:38AM
Yeah, for me I just turned 8 into X (less temptation to do maths on the “8”) and added the exponents.

I’ll also vote that you’re right.
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Re: Math problem with exponents and radicals
Posted by: Lux Interior
Date: October 26, 2021 11:19AM
Quote
srf1957
7.999999996

8.000000008
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Re: Math problem with exponents and radicals
Posted by: N-OS X-tasy!
Date: October 26, 2021 05:16PM
Quote
srf1957
7.999999996

Brought to you by the Intel Pentium chip!



It is what it is.
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