Im not quite sure how you are using K but generally.....
=if(x<72,your formula,if(and(x72,x<300),your formula,"Error")
This does not take into account x=72 you may need to adjust accordingly.
Also with this formula if x=72 then the formula will return error

"Blades" wrote:

Hi

I am trying to discover a formula/function that will allow me to do the
following!

my problem is this:

x = 100mm

if x <72 then k = 1.17
if 72 < x< 300 then k = (300/x)^0.11

can anyone tell me how i can combine these into one function?

cheers rich