SOLUTION: Solve for c: 54=(2c)+22.5+(5.7/c)

Algebra ->  Expressions-with-variables -> SOLUTION: Solve for c: 54=(2c)+22.5+(5.7/c)      Log On


   

Question 85627: Solve for c:
54=(2c)+22.5+(5.7/c)
Found 2 solutions by scianci, stanbon:
Answer by scianci(186) About Me  (Show Source):
You can put this solution on YOUR website!
Isolate the variables:
54 - 22.5 = 2c + 5.7%2Fc
31.5 = 2c + 5.7%2Fc
Multiply everything by c:
31.5c = 2c%5E2 + c5.7%2Fc
31.5c = 2c%5E2 + 5.7
Set = 0:
2c%5E2 - 31.5c + 5.7 = 0
Multiply by 10 [to shift the decimal points]:
20c%5E2 - 315c + 57 = 0
Apply the quadratic formula:
x = %28-b+%2B-+sqrt%28b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
= %28315+%2B-+sqrt%28%28-315%29%5E2-4%2A20%2A57+%29%29%2F%282%2A20%29+
= %28315+%2B-+sqrt%2899%2C225-4560%29%29%2F40
= %28315+%2B-+sqrt%2894%2C665%29%29%2F40

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Solve for c:
54=(2c)+22.5+(5.7/c)
2c-31.5+(5.7/c)=0
-----------------
Multiply thru by c to get:
2c^2-31.5c+5.7 = 0
20c^2-315c+57 = 0
c=[315+-sqrt(315^2-4*20*57)/40
c=[315+-307.68]/40
c= 0.18 or c=15.57
graph%28400%2C300%2C-5%2C20%2C-1200%2C750%2C20x%5E2-315x%2B57%29
===========
Cheers,
stan H.