If $625^{-x}+25^{-2x}+5^{-4x}=15,$ what is the value of $x?$

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Gmat_mission: Legendary Member; Posts: 1622; Joined: Thu Mar 01, 2018 7:22 amFollowed by: 2 members

by Gmat_mission » Sun Oct 18, 2020 11:31 am

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If $625^{-x}+25^{-2x}+5^{-4x}=15,$ what is the value of $x?$

A. -4
B. -1/4
C. 0
D. 1/4
E. 4

Answer: B

Source: GMAT Club Tests

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Source: Beat The GMAT — Problem Solving | Sun Oct 18, 2020 11:31 am

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