Is $f (x) = (x - 2) (x + 5) (x - 1)$ $f(x)=(x-2)(x+5)(x-1)$ increasing or decreasing at $x = - 1$ $x=-1$ ?

Question

Is $f (x) = (x - 2) (x + 5) (x - 1)$ $f(x)=(x-2)(x+5)(x-1)$ increasing or decreasing at $x = - 1$ $x=-1$ ?

1 Answer

Impact of this question

1641 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-11-06T20:21:07

$f (x)$ $f(x)$ is decreasing when $x = - 1$ $x=-1$

Explanation:

To determine whether $f (x)$ $f(x)$ is increasing or decreasing at $x = - 1$ $x=-1$ , we have to check whether $f'(x)$ is positive or negative at $x=-1$ .

First, find $f'(x)$ using product rule:
$f(x) = (x-2)(x+5)(x-1)$
$f'(x) = cancel((1))(x+5)(x-1) + (x-2)cancel((1))(x-1) + (x-2)(x+5)cancel((1))$
$f'(x) = 3x^2+4x-13$

Next, find $f'(-1)$ :
$f'(-1)=-14$

Since $f'(-1)$ is negative, that means that $f(x)$ is decreasing when $x=-1$ .

Science

Math

Humanities

... and beyond

Is $f (x) = (x - 2) (x + 5) (x - 1)$ $f(x)=(x-2)(x+5)(x-1)$ increasing or decreasing at $x = - 1$ $x=-1$ ?

1 Answer

Explanation:

Related questions

Impact of this question

Science

Math

Humanities

... and beyond

Is f(x)=(x-2)(x+5)(x-1)f(x)=(x−2)(x+5)(x−1)f(x)=(x-2)(x+5)(x-1) increasing or decreasing at x=-1x=−1x=-1?

1 Answer

Explanation:

Related questions

Impact of this question

Is $f (x) = (x - 2) (x + 5) (x - 1)$ $f(x)=(x-2)(x+5)(x-1)$ increasing or decreasing at $x = - 1$ $x=-1$ ?