Tricky Exponents Questions
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2^(x+2)3(2^(x1))=(5/8)(2^(16x))
4*2^x(3/2)*2^x=(5/2^3)((2^16)/2^x)
let 2^x=m
4*m(3/2)*m=(5*(2^13))/m
(5/2)*m=(5*(2^13))/m
m/2=(2^13)/m
m^2=2^14
replacing m=2^x
2^(2x)=2^14
2x=14
x=7
4*2^x(3/2)*2^x=(5/2^3)((2^16)/2^x)
let 2^x=m
4*m(3/2)*m=(5*(2^13))/m
(5/2)*m=(5*(2^13))/m
m/2=(2^13)/m
m^2=2^14
replacing m=2^x
2^(2x)=2^14
2x=14
x=7
 GMATGuruNY
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We can plug in the answer choices, which represent the value of x:
Answer choice C: x=7.
2^(7+2)  3 * 2^(71) = 5/8 * 2^(167)
2â�¹  3(2â�¶) = 5/(2Â³) * 2â�¹
2â�¶(2Â³  3) = 5 * 2â�¶
2â�¶ * 5 = 5 * 2â�¶. Success!
The correct answer is C.
Answer choice C: x=7.
2^(7+2)  3 * 2^(71) = 5/8 * 2^(167)
2â�¹  3(2â�¶) = 5/(2Â³) * 2â�¹
2â�¶(2Â³  3) = 5 * 2â�¶
2â�¶ * 5 = 5 * 2â�¶. Success!
The correct answer is C.
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 kevincanspain
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The key is to factor out either 2^(x+2) or 2^(x1) from the left side. I chose the former because it will give a fractional cooefficienttonebeeze wrote:Can someone please walk me step by step through the simplification process of this problem. I got lost along the way...lol. Thanks!
(2^(x+2))(1 3(2^3)) = (5/8)(2^(x+2))
Since LS=RS
x+ 2 = 16  x
x=7
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 Ian Stewart
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I replied to your post about this question on another forum, so I'll just paste the link:
https://gmatclub.com/forum/trickyexpone ... 12271.html
https://gmatclub.com/forum/trickyexpone ... 12271.html
If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

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@MitchGMATGuruNY wrote:We can plug in the answer choices, which represent the value of x:
Answer choice C: x=7.
2^(7+2)  3 * 2^(71) = 5/8 * 2^(167)
2â�¹  3(2â�¶) = 5/(2Â³) * 2â�¹
2â�¶(2Â³  3) = 5 * 2â�¶
2â�¶ * 5 = 5 * 2â�¶. Success!
The correct answer is C.
Isn't this method gonna be very lengthy and time taking???
 HSPA
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In LHS : take the common value ie 2^(x1) seperately..
2^(x1) (83) = 5(2^(13x))
x1 = 13x
IMO 7
2^(x1) (83) = 5(2^(13x))
x1 = 13x
IMO 7
First take: 640 (50M, 27V)  RC needs 300% improvement
Second take: coming soon..
Regards,
HSPA.
Second take: coming soon..
Regards,
HSPA.
Brilliant!!! I can confidently say I understand how its doneIan Stewart wrote:I replied to your post about this question on another forum, so I'll just paste the link:
https://gmatclub.com/forum/trickyexpone ... 12271.html
Thank you