Thread: Exponential and logarithmic Functions help

I have the equation y = 15^x which determines the population and x is how many days.

Determine to the nearest day when the population will reach 600.

How do I figure out the above without just guess and check?

You can set and take logarithms on both side to solve for .

Originally Posted by olen12

I have the equation y = 15^x which determines the population and x is how many days.

Determine to the nearest day when the population will reach 600.

How do I figure out the above without just guess and check?

guess and check will work fine unless your calculator can calculate base 15, then...

Originally Posted by pickslides

guess and check will work fine unless your calculator can calculate base 15, then...

Even if your calculator does NOT have a logarithm, base 15, You can do using log base 10 (common log) [tex]log_{10} 600= log_{10}(15^x)= x log_{10}(15)[tex] so .

Or with the natural logarithm key, "ln", so .