Question 67939
2ne level / 1st level = 3rd level/2nd level

or
x /50 = x+50/x

a. Determine what wattage (x) should be used for the 2nd filament to meet the desired conditions. 
x /50 = x+50/x
Cross-multiply to get:
x^2=50x+2500
x^2-50x-2500=0
x is appox 80.9 watts


b. Check the results of part A. What is the ratio of 2nd to 1st filament wattage? What is the ratio of 3rd to 2nd? Do they match?

80.9/50 = 130.9/80

6544.81 appoximately 6545
---------------

c. Suppose the 1st filament is only 40 watts. what would that wattage of the 2nd filament need to be?
x/40 = x+40/x
x^2=40x+1600
x^2-40x-1600=0
x is approx 64.7
----------------
Cheers,
Stan H>