Question #26c4a

1 Answer
Nov 28, 2017

x=6
See explanation.

Explanation:

I assume you mean the following: 81^x = 27^(-x+14)
So I notice here that 81=9^2=3^4 and that 27=3^3.
Let's rewrite the equation as such:
(3^4)^x = (3^3)^(-x+14)

Then, this becomes:
3^(4x) = 3^(3(-x+14))
because exponents of exponents get multiplied.

We can now simplify this by equating just the exponents:
4x = 3*(-x+14)

We now simply solve this equation, so opening up the parentheses and keeping simplifying, we get:
4x = -3x +42
i.e.
7x = 42
i.e.
x = 6