Given the function f(x)=x2−x+1
To find where the function is increasing or decreasing, find the derivative:
f′(x)=2x−1
Setting f′(x)=0 to find the critical point:
2x−1=0
2x=1
x=21
For x<21, test x=0:
f′(0)=2(0)−1=−1
Since f′(0)<0, the function is decreasing on (−∞,21)
For x>21, test x=1:
f′(1)=2(1)−1=1
Since f′(1)>0, the function is increasing on (21,∞)
The function is:
Decreasing on (−∞,21)
Increasing on (21,∞)