Solve 2+5^x=15

$$2 + 5 ^ { x } = 15$$

Solve for x

$$x=\log_{5}\left(13\right)\approx 1.593692641$$

Steps Using Definition of Logarithm

Use the rules of exponents and logarithms to solve the equation.

$$5^{x}+2=15$$

Subtract 2 from both sides of the equation.

$$5^{x}=13$$

Take the logarithm of both sides of the equation.

$$\log(5^{x})=\log(13)$$

The logarithm of a number raised to a power is the power times the logarithm of the number.

$$x\log(5)=\log(13)$$

Divide both sides by \log(5).

$$x=\frac{\log(13)}{\log(5)}$$

By the change-of-base formula \frac{\log(a)}{\log(b)}=\log_{b}\left(a\right).

$$x=\log_{5}\left(13\right)$$

Solve for x (complex solution)

$$x=\frac{2\pi n_{1}i}{\ln(5)}+\log_{5}\left(13\right)$$

$$n_{1}\in \mathrm{Z}$$