Solve 3(5^x)-21=54

$$3 ( 5 ^ { x } ) - 21 = 54$$

Solve for x

$$x=2$$

Steps Using Definition of Logarithm

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

$$3\times 5^{x}-21=54$$

Add 21 to both sides of the equation.

$$3\times 5^{x}=75$$

Divide both sides by 3.

$$5^{x}=25$$

Take the logarithm of both sides of the equation.

$$\log(5^{x})=\log(25)$$

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

$$x\log(5)=\log(25)$$

Divide both sides by \log(5).

$$x=\frac{\log(25)}{\log(5)}$$

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

$$x=\log_{5}\left(25\right)$$

Solve for x (complex solution)

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

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