View Full Version : Simplify fraction
songoku
Jan19-12, 10:26 PM
1. The problem statement, all variables and given/known data
Simplify
\frac{2}{49^{1/3}+7^{1/3}+1}
2. Relevant equations
3. The attempt at a solution
I can simplify
\frac{2}{49^{1/3}+7^{1/3}}
but I don't have idea how to do this one..
EDIT: I have found it. No need to reply this. Thanks :)
1. The problem statement, all variables and given/known data
Simplify
\frac{2}{49^{1/3}+7^{1/3}+1}
...
3. The attempt at a solution
I can simplify
\frac{2}{49^{1/3}+7^{1/3}}
but I don't have idea how to do this one..
EDIT: I have found it. No need to reply this. Thanks :)
I see that you have found it, but for others looking later:
Multiply the numerator & denominator by \displaystyle (7^{1/3}-1)
songoku
Jan20-12, 12:14 AM
I see that you have found it, but for others looking later:
Multiply the numerator & denominator by \displaystyle (7^{1/3}-1)
I did it another way but let discuss your way. I drop the numerator because we only concern about the denominator.
After multiplying it with 71/3 - 1, I get:
491/3 . 71/3 - 491/3 + 72/3 - 1
I think I have to multiply the denominator with another term but I can't find it..
49=72 so the denominator becomes 6 .
491/3 ∙ 71/3 - 491/3 + 72/3 - 1
= 72/3 ∙ 71/3 - 72/3 + 72/3 - 1
= 7 - 1
songoku
Jan20-12, 02:31 AM
49=72 so the denominator becomes 6 .
491/3 ∙ 71/3 - 491/3 + 72/3 - 1
= 72/3 ∙ 71/3 - 72/3 + 72/3 - 1
= 7 - 1
It really didn't cross my mind; multiplying with (71/3 - 1) will directly give the answer. Your method is much simpler than mine. I should have noticed the pattern a^2 + a + 1 in the denominator, which can be simplified by multiplying it with (a - 1)
Thanks :)
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