Exponent -- Difficult One... I think

Question

*Edited:

(5^21)*(4^11) = 2x10^N, solve for N.

What is N

Please put down a solid explanation. Thanks!

Damager · Answer

Something wrong with question

ashkrs · Answer

Somethings wrong in questions.

(4^28) * (5^57)
(2^56) * ( 5^57)

 1/2 * ( 10^57)

So question should be probably like this

(4^28) * (5^57) = 1/2 x 10^N
Find N

dominion · Answer

Actually, no -- this is the exact question from GMATPrep1 -- 

(5^21)*4^11 = 2x10^N, solve for N.

aspratap08 · Answer

N = 21... Here is the explanation... 

5^21 * 4 ^ 11 = 2 * 10 ^ N
5^21 * 2 ^ 22 = 2 * 10 ^ N
(5*2)^21 * 2 = 2 * 10 ^ N
N = 21.

walker · Answer

(5^21)*(4^11) = 2x10^N
(5^21)*(2^22) = 2x(2*5)^N
(5^21)*(2^22) = 5^N*2^(N+1)
N=21

ashkrs · Answer

great ! ashkrs :arrow:

marcodonzelli · Answer

the equation equals: 5^21*2^22=2*10^n.........10^21*2=2*10^n.......n=21

Amit05 · Answer

21 it is ..

5^21 * 4^11 = 2*10^n
5^21 * 2^2^11 = 2*10^n
5^21 * 2^22 = 2*10^n
5^21 * 2^21*2 = 2*10^n
10^21*2 = 2*10^n
n=21

hotdog · Answer

That's a great question. I ran into it this morning and it gave me difficulty too. Embarrassing how simple it is to solve....tricky! :oops:

vscid · Answer

21 indeed. thoght it was a cakewalk.

Exponent -- Difficult One... I think

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