Given a polynomial of degree 5, get minimum and maximum without using derivatives

2.1k Views Asked by At

Given a quintic polynomial (in my case, $x^5+2x^4+16x-32$), I am supposed to get its maximum and minimum value for the interval $I=[-2;2]$ without using the derivative of the corresponing polynomial function.

I remember that for quadratic functions, there was a trick that required you to factor your polynomial and then maximize or minimize all of the factors.

But how would I do this for polynomials of higher degrees?

1

There are 1 best solutions below

1
On BEST ANSWER

We have $$ x^5+2x^4+16x-32=(x+2)(x^4+16) - 64 $$ First term is always non-negative on the given interval (hence minimum is attained at $-2$), and increasing, as is easy to show without using derivatives.