Question

Find the derivative of f(x) = 7x + 9 at x = 6

Answer 1

F(x)=7x+9
f´(x)=7
f´(6)=7

answer: f´(6)=7

f´(x)=Lim x⇒0   (f(x+h)-f(x)) / h
f´(6)=lim x⇒ 0   (7(6+h)+9 -(7*6+9)) / h
=lim x⇒0 ( 42+7h+9-42-9) /h
=lim x⇒0 (7h/h)=7

answer: f´(6)=7