How do you verify the intermediate value theorem over the interval [0,3], and find the c that is guaranteed by the theorem such that f(c)=4 where f(x)=x^3-x^2+x-2f(x)=x3x2+x2?

2 Answers
Aug 14, 2017

ff is a polynomial so ff is continuous on the interval [0,3][0,3].

f(0) = -2f(0)=2 and f(3) = 19f(3)=19

44 is between f(0)f(0) and f(3)f(3) so IVT tells us that there is a cc in (0,3)(0,3) with f(c) = 4f(c)=4

Finding the cc requires solving

x^3-x^2+x-2 = 4x3x2+x2=4. Which is equivalent to

x^3-x^2+x-6 = 0x3x2+x6=0

Possible rational zeros are +-1±1, +-2±2, +-3±3, and +-6±6.

Testing shows that 22 is a solution.

So c = 2c=2

Aug 14, 2017

The value of c in (0, 3)c(0,3) and is c=2c=2

Explanation:

The intermediate value theorem states that if f(x)f(x) is a continuous function on the interval [a,b][a,b], then there is a number pp between f(a)f(a) and f(b)f(b), (f(a)!=f(b))(f(a)f(b)) such that there is a number c in (a,b)c(a,b) such that p=f(c)p=f(c)

Here, f(x)=x^3-x^2+x-2f(x)=x3x2+x2, which is a polynomial function continuous on the Interval [0,3][0,3]

f(0)=0-0+0-2=-2f(0)=00+02=2

f(3)=3^3-3^2+3-2=27-9+3-2=19f(3)=3332+32=279+32=19

f(c) in (f(0, f(3)))f(c)(f(0,f(3)))

f(c)=4f(c)=4 such that c in (0,3)c(0,3)

Therefore,

f(c)=c^3-c^2+c-2=4f(c)=c3c2+c2=4

=>, c^3-c^2+c-6=0c3c2+c6=0

f(2)=2^3-2^2+2-2=8-4+2-2=4f(2)=2322+22=84+22=4