How do I find all the critical points of f(x)=(x-1)^2f(x)=(x1)2?

1 Answer
Oct 29, 2015

See the explanation.

Explanation:

The critical numbers for a function ff and the numbers in the domain of ff, at which either f(x)f(x) does not exist or f(x)=0f(x)=0.

For f(x)=(x-1)^2f(x)=(x1)2, note that the domain is (-oo,oo)(,).

Find f'(x)
We can use the power and chain rule to get:

f'(x) = 2(x-1)^1 d/dx(x-1) = 2(x-1)(1) = 2(x-1)

Or we can expand f(x) = x^2-2x+1 and differentiate this polynomial:

f'(x) = 2x-2
Find the critical numbers for f

Either way, we see that
f'(x) is never undefined and f'(x) = 0 at x=1#.

1 is in the domain of f, so it is a critical numbers for f.

The "critical points" are (most commonly), the same as critical numbers.
But some use a variant terminology in which critical points are points on the graph, so the have both x and y coordinates.

If you are in such a situation, you need to find y when x=1 to finish.

y=f(1) = 0, so the point on the graph is (1,0)