From my notes I’ve the derivative of arctan(x)= 1/(1+x^2)
Answer: x = 2
Step-by-step explanation:

Replace y in the first equation by the value of y in the second equation.

Answer: 60.875
Step-by-step explanation:
57+59+60+60+61+61+64+65= 487
then 487/8= 60.875