Answer:
Step-by-step explanation:
![a.\\\frac{d}{dx}(\frac{-1}{1+x^2} )=\frac{d}{dx} [-1(1+x^2)^{-1}]=-1(-1)(1+x^2)^{-2}(2x)=\frac{2x}{(1+x^2)^2 }\\](https://tex.z-dn.net/?f=a.%5C%5C%5Cfrac%7Bd%7D%7Bdx%7D%28%5Cfrac%7B-1%7D%7B1%2Bx%5E2%7D%20%29%3D%5Cfrac%7Bd%7D%7Bdx%7D%20%5B-1%281%2Bx%5E2%29%5E%7B-1%7D%5D%3D-1%28-1%29%281%2Bx%5E2%29%5E%7B-2%7D%282x%29%3D%5Cfrac%7B2x%7D%7B%281%2Bx%5E2%29%5E2%20%7D%5C%5C)
b.
put 1+x²=u
2x dx=du
when x=0,u=1
when x=2,u=1+2²=5

Answer: Sally walked 3 minutes faster per mile
Hope it helped!
Answer:
y intercept is -1/2
Step-by-step explanation:
You can plug in the numbers
1) (0,3):
3 < 2(0) + 2
3 < 2 this is incorrect, so it is not 1
2) (2,0)
0 < 2(2) + 2
0 < 6 this passed the first one
0 > -(2) - 1
0 > -3 this is also correct
the answer is 2) (2,0)