SOLUTION: Solve for X: e^x+3e^-x-18=0

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Question 36046: Solve for X:
e^x+3e^-x-18=0
Answer by venugopalramana(3286) About Me  (Show Source):
You can put this solution on YOUR website!
Solve for X:
e^x+3e^-x-18=0...........LET E^X=Y..THEN....E^(-X)=1/E^X=1/Y...HENCE
Y+3/Y-18=0....MULTIPLYING WITH Y
Y^2-18Y+3=0
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
Y+=+%2818+%2B-+sqrt%28+18%5E2-4%2A1%2A3+%29%29%2F%282%2A1%29+
Y+=+%2818+%2B-+sqrt%28+312+%29%29%2F%282%29+
Y+=+%289%2B-+sqrt%28+78+%29%29+=E^X
TAKING LOGS ON BOTH SIDES TO BASE E,WE GET
X=2.88 OR -1.78