# Logarithms help

If $2000 is invested at a rate of 12 percent per year, what is the principle after 5 years if the interest is compound quarterly? What is the principle afetr 5 years if the interest is compound quarterly? Thanks to anyone who can solve. • Apr 29th 2008, 10:57 AM james_bond Is it$\displaystyle 2000\cdot 1.03^{20}=3612.22$? (There are$\displaystyle 5*4=20$"compounds" with$\displaystyle 12/4=3 \%$.) I'm not sure as there are no logarithms in it... • Apr 29th 2008, 12:40 PM av8or91 Doesnt the compund interest formula contain logarithms? • Apr 29th 2008, 12:43 PM icemanfan Quote: Originally Posted by av8or91 Doesnt the compund interest formula contain logarithms? The formula is$\displaystyle A = P(1 + \frac{r}{t})^{nt}$where r is the annual rate, t is the number of periods per year, n is the number of years, and P is the principal. So there are no logarithms in the formula. • Apr 30th 2008, 11:27 AM av8or91 Alright thanks for the reply. I have one logarithm problem I cant figure out Log2x^3= Log2(6-x) • Apr 30th 2008, 12:01 PM topsquark Quote: Originally Posted by av8or91 Alright thanks for the reply. I have one logarithm problem I cant figure out Log2x^3= Log2(6-x) New questions go in new threads.$\displaystyle log_2(x^3) = log_2(6 - x)\displaystyle x^3 = 6 - x\displaystyle x^3 + x - 6 = 0\$