# Thread: Help with solving exponential/log equations

1. ## Help with solving exponential/log equations

Solve the exponential equation. Use a calculator to obtain a decimal approximation, correct to two decimal places, for the solution.

7^x=6^(x+7)

Solve the logarithmic equation. Be sure to reject any value that is not in the domain of the original logarithmic expressions. Give the exact answer.

log10 (x-30)= 3 - log10 x

2. On the top, use the power rule (see other post I answered).

x ln 7 = x + 7 ln 6

That is a messy equation.

Divide each side by (x + 7).

$\displaystyle \frac {x ln 7}{x + 7}$
According to a logarithmic rule (whose name alludes me),
$\displaystyle \frac {ln 7}{7}$ .

Then solve with your calculator with decimal place for 2 places.

That "logarithmic rule" probably doesn't exist so you better wait for another answer.

For the second problem,
Remember that log 10 = 1.
The solve.
I don't know what it means by
Be sure to reject any value that is not in the domain of the original logarithmic expressions.