Given the function f(x)=3x^3−2xf(x)=3x32x, how do you determine whether f satisfies the hypotheses of the Mean Value Theorem on the interval [-4,4] and find the c?

1 Answer
Apr 1, 2017

The values of cc are =+-2.31=±2.31

Explanation:

The mean value states theorem that if a function is continous on an

interval [a,b][a,b] and derivable on the interval ]a,b[]a,b[, then there is a

point c in [a,b] c[a,b] such that f'(c)=(f(b)-f(a))/(b-a)

Here,

f(x)=3x^3-2x is a polynomial function, defined, continuous and derivable on the interval x in [-4,4]

f'(x)=9x^2-2

f(-4)=3*(-4)^3+8=-192+8=-184

f(4)=3*4^3-8=184

Therefore,

f'(c)=(f(4)-f(-4))/(4+4)=(184+184)/8=46

f'(c)=9c^2-2=46

c^2=(46+2)/9=sqrt48/3

c=+-4sqrt3/3=+-2.31

Therefore,

c in [-4,4]