Another approach to the problem, which avoids Solver altogether, is to note
that this is a quartic equation in x=exp(-y/2). Quartic equations have known
solutions
http://en.wikipedia.org/wiki/Quartic_equation
Ferrari's method has a solution with real x0 [so that y=-2*ln(x) is also
real] by taking +/-[s] to be - and +/-[t] to be + to get
x=0.97209229125665744 or y=-2*ln(x)=0.056609058353243358

Jerry

"Josh P." wrote:

Hello, my question deals with solver and exponents in excel. This may be too
technical but I'll give it a try. I'm using solver for calculating zero rate
or "spot rate" bond yields. Instead of using periodic interest rates you
have to use continuous compounding. Here is the formula with the numbers
inputed and I'll use "Y" as the variable to solve for:

4(EXP-(Y*.5)) +4(EXP-(Y*1))+4(EXP-(Y*1.5))+104(EXP-(Y*2.0))

all of this must equal 104.21 when the equation is solved out. My teacher
showed us the answer in class but didn't go over the technique cause he
assumed we could figure it out. I'm unsure of how to do it with solver. Any
help would be greatly appreciated and I'll be glad to answer any questions.
Thanks