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Re: Exponents

by Morgoth » Sun Oct 19, 2008 1:17 am
csandeepreddy wrote:Which of the following best approximates the value of q if 5^28+3^11=5^q ?

a. 39
b. 30
c. 28
d. 27
e. 17
5^28+3^11=5^q

3^3 ~ 5^2

5^28 + 3^2 * 5^6 = 5^q

5^6 (5^22 + 3^2) = 5^q

5^6 * 5^22 = 5^q

5^28 = 5^q

q = 28


OA?
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by csandeepreddy » Sun Oct 19, 2008 4:23 am
The OA is C.

Thanks Morgoth
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Re: Exponents

by kanha81 » Sat May 30, 2009 10:12 am
Morgoth wrote:
csandeepreddy wrote:Which of the following best approximates the value of q if 5^28+3^11=5^q ?

a. 39
b. 30
c. 28
d. 27
e. 17
5^28+3^11=5^q
3^3 ~ 5^2
I don't understand the following deduction-
Morgoth wrote: 5^28 + 3^2 * 5^6 = 5^q

can someone please explain?
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Re: Exponents

by exhilaration » Sat May 30, 2009 10:20 am
kanha81 wrote:
Morgoth wrote:
csandeepreddy wrote:Which of the following best approximates the value of q if 5^28+3^11=5^q ?

a. 39
b. 30
c. 28
d. 27
e. 17
5^28+3^11=5^q
3^3 ~ 5^2
I don't understand the following deduction-
Morgoth wrote: 5^28 + 3^2 * 5^6 = 5^q

can someone please explain?
3^3 ~ 5^2

So... 3^11 = 3^3 * 3^3 * 3^3 * 3^2

Substitute 5^2 for 3^3 and you get 5^2 * 5^2 * 5^2 * 3^2 = 5^6 * 3^2

Factor out the 5^6 and you get 5^6 (5^22+3^2) -> The 3^2 is negligible
when compared to 5^22, thus your answer is 5^6 * 5^22 = 5^28 and p = 28.
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