exponential equation: Solve for x: 5*4^x-3=40

[ruffnite]

Solve for x: 5*4^x-3=40

I am pretty stumped on getting a base number for the right side of the equation to equal the left side.
I tried by dividing both sides by 5 but it gave me: 4^x-3=8

Any help is appreciated thx.

 

[wjm11]

Re: exponential equation

Solve for x: 5*4^x-3=40

I am pretty stumped on getting a base number for the right side of the equation to equal the left side.
I tried by dividing both sides by 5 but it gave me: 4^x-3=8

If the exponent is x-3, you need to show this with parentheses:

5(4^(x-3)) = 40

As you said, divide both sides by 5:

4^(x-3) = 8

Next, recognize that both 4 and 8 are powers of 2:

(2^2)^(x-3) = 2^3

2^(2x-6) = 2^3

2x-6 = 3

Hope that helps.

 

[ruffnite]

Many thanks. I will use parentheses properly next time.