Posted by **jen** on Tuesday, February 19, 2008 at 5:57pm.

243^(.2x)= 81^(x+5)

- math -
**Reiny**, Tuesday, February 19, 2008 at 7:05pm
both 243 and 81 are powers of 3

243 = 3^5 and 81 = 3^4

so rewrite your equation:

243^(.2x)= 81^(x+5)

(3^5)^(.2x) = (3^4)^(x+5)

3^x = 3^(4z+20)

If the bases are the same, for the equation to be true, obviously the exponents have to be the sam

so x = 4x+20

x = -20/3

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