# Math Help - Logarithms help

1. ## Logarithms help

If \$2000 is invested at a rate of 12 percent per year, what is the principle after 5 years if the interest is compound quarterly? What is the principle afetr 5 years if the interest is compound quarterly?

Thanks to anyone who can solve.

2. Is it $2000\cdot 1.03^{20}=3612.22$? (There are $5*4=20$ "compounds" with $12/4=3 \%$.)
I'm not sure as there are no logarithms in it...

3. Doesnt the compund interest formula contain logarithms?

4. Originally Posted by av8or91
Doesnt the compund interest formula contain logarithms?
The formula is $A = P(1 + \frac{r}{t})^{nt}$ where r is the annual rate, t is the number of periods per year, n is the number of years, and P is the principal. So there are no logarithms in the formula.

5. Alright thanks for the reply.

I have one logarithm problem I cant figure out

Log2x^3= Log2(6-x)

6. Originally Posted by av8or91

I have one logarithm problem I cant figure out

Log2x^3= Log2(6-x)
New questions go in new threads.

$log_2(x^3) = log_2(6 - x)$

$x^3 = 6 - x$

$x^3 + x - 6 = 0$

There are no "nice" solutions to this equation, so it isn't surprising that you haven't been able to solve it. Numerically I get x = 1.634365293.

-Dan