If f(x)=4arctan(7x), find f'(x). Find f'(4).

f'(x) = (4 arctan(7x))'

f'(x) = 4 (arctan(7x))'

By the chain rule,

f'(x) = 4/(1 + (7x)^2) * (7x)'

f'(x) = 28/(1 + 49x^2)

and hence

f'(4) = 28/(1 + 49*16) = 28/785

In case you're not sure about the derivative of arctan: If y = arctan(x), then x = tan(y). Differentiating both sides with respect to x gives

1 = sec^2y y' = (1 + tan^2y) y' = (1 + x^2) y'

==>  y' = 1/(1 + x^2)

is means division by fractions

step-by-step explanation:

step-by-step explanation:

you can add the two numbers and divide the result by 2. or you can find the gap between the two numbers and add half of this to the smaller number.