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Problem Solving_ Exponents

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Problem Solving_ Exponents

by mlamaiti2003 » Fri Oct 31, 2008 7:15 am
which of the following is equal to: 2^5 + 2^5 + 3^5 + 3^5 + 3^5?

A. 5^6
B. 13^5
C. 2^6 + 3^6 (correct answer)
D. 2^7 + 3^8
E. 4^5 + 9 ^5

First question on the GMATPREP practice test 1.

Please show how to solve?

Thank you
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by jbramet » Fri Oct 31, 2008 7:53 am
Hello,

Do not forget that you are Adding them and not Multiplying,

The rule is a^x + a^x = 2 a^x

Therefore you have:

2 * (2^5) and 3 * (3^5)

Therefore:

2^6 + 3^6

Hope it helps,

JB
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by raunekk » Fri Oct 31, 2008 8:03 am
2^5 + 2^ 5 = 2 ( 2^5) = 2 ^ ( 5+1) = 2^ 6

3^5 + 3^5 + 3^5= 3(3^5) = 3 ^ (5+1) = 3 ^6

thus 2^6 + 3 ^ 6

hence C
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by smallsorrow » Fri Oct 31, 2008 9:07 am
FActor out

= 2^5(1+1) + 3^5 (1+1+1)
= 2^5(2) + 3^5 (3)
= 2^6+3^6
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