Questions on Algebra: Functions, Domain, NOT graphing answered by real tutors!

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Question 150581: f(x)= x+1/3x-1
find the value of c if f(c)=c: f(x)= x+1/3x-1
find the value of c if f(c)=c
Answer by Fombitz(1740) About Me  (Show Source):
You can put this solution on YOUR website!
f(x)=(x+1)/(3x-1)
If f(c)=c, then
(c+1)/(3c-1)=c
(c+1)=c(3c-1)
c+1=3c^2-c
3c^2-2c-1=0
Using the quadratic formula to solve for c,
c = (-(-2) +- sqrt( (-2)^2-4*3*(-1) ))/(2*3)
c = (2 +- sqrt( 4+12))/(6)
c = (2 +- sqrt( 16))/(6)
c = (2 +- 4)/(6)
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c[1] = (2 + 4)/(6)
c[1] = (6)/(6)
c[1] = 1
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c[2] = (2 - 4)/(6)
c[2] = (-2)/(6)
c[2] = -(1/3)