Chegg solution manual says fx 3 f1x lim delta x 0 fxdeltax
Chegg solution manual says:
f(x) = 3
f1(x) = lim delta x ->0 f(x+deltax) - f(x)/delta x
 
=lim delta x -> 0 3-3/delta x
 
My question is why did the delta x suddenly drop from the numerator?
When I was doing the question my step was:
 
(3+ delta x) +3/delta x
f(x) = 3
f1(x) = lim delta x ->0 f(x+deltax) - f(x)/delta x
=lim delta x -> 0 3-3/delta x
My question is why did the delta x suddenly drop from the numerator?
When I was doing the question my step was:
(3+ delta x) +3/delta x
Solution
it should be (3- 3)/delta x because the function is constant function and no variable x exist so f(x) and f(x+ delta x) are one and the same for any value of delta x
