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exponents

by simba12123 » Tue Nov 04, 2008 8:51 pm
If x and y are integers and

(15x + 15^(x+1))/ 4y = 15y,

what is the value of x?

2
3
4
5
Cannot be determined


cant we backsolve this bad boy? What is the best and most sure shot way?
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by canuckclint » Tue Nov 04, 2008 9:14 pm
i say it cannot be determined because we don't know y.
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by vishubn » Tue Nov 04, 2008 9:27 pm
Is the problem free of typo????


i mean x and y !! two different unknowns !! First glance one can know "IT CANT BE DETERMINED"

any more comments???


Vishu
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Re: exponents

by logitech » Tue Nov 04, 2008 9:51 pm
simba12123 wrote:If x and y are integers and

(15x + 15^(x+1))/ 4y = 15y,

what is the value of x?

2
3
4
5
Cannot be determined


cant we backsolve this bad boy? What is the best and most sure shot way?
There has to be a typo. I assume that the questions reads like this:

(15^X + 15^(x+1))/ 4y = 15y

SO;

15^x+15^x15=15 4y^2

15^x(15+1)=15 4y^2

15^x = (15 y^2 ) /4

SO I belive this is where the magic is:

8)

15^x = 15 (y^2 /4)

15^x can be 1, 15, 15^2,....

Who wants to take it from here ?
:lol:
LGTCH
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by vishubn » Tue Nov 04, 2008 10:02 pm
Who wants to take it from here ?
Laughing
so further doing it !!
we knw x and y are integers

y^2=((15^x)*4)/15

so Left hand side should be a perfect square

a) we get y^2=60 not a perfect square
b) we get y^2=900 and y=30 , possible answer
c)we get y^2=13500 not a perfect square
d) we get y^2=202500 y=450 , possible answer !!

stuck betwwen B and D

Any more attemptS??

Vishu
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by raunekk » Tue Nov 04, 2008 10:41 pm
there is a typo here,,,

https://www.beatthegmat.com/i-don-t-unde ... 15609.html


thanks,...
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by logitech » Tue Nov 04, 2008 10:51 pm
raunekk wrote:there is a typo here,,,

https://www.beatthegmat.com/i-don-t-unde ... 15609.html


thanks,...
Thanks man! - I mean MAJOR TYPO!!
LGTCH
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by vishubn » Wed Nov 05, 2008 12:05 am
WOW!!!
Way tooo off league !!

Vishu

thanks again
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yes

by simba12123 » Wed Nov 05, 2008 8:23 am
Logitech hit the nail on the head. The question does stand corrected!
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Re: yes

by jimmiejaz » Wed Nov 05, 2008 8:43 am
simba12123 wrote:Logitech hit the nail on the head. The question does stand corrected!
He corrected it on part :)
the powers of y also needed to be corrected!!!!!!
anyways keep rocking guys!!!!!
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