Question

find the derivative of x > a using lim (f(x) - f(a))/(x-a)

Answer 1

derivative of x > a?

Answer 2

Woops, had a brain fart. The derivative of the function 4x - 3x^2 using the equation f(x) - f(a) / (x - a)

Answer 3

dx is such a small element that the curve can be considered as a straight line,,
long story cut short , you have to use this :
f(x+dx) -f(x) / (x+dx - x)

where, f(x) = 4x -3x^2

so we have

4(x+dx) - 3(x+dx)^2 - 4x + 3x^2 / (dx)
=> 4x + 4dx - 3x^2 - 3dx^2 - 6xdx -4x +3x^2/ dx
=>4dx - 3dx^2 - 6xdx / dx
=>4 - 3dx - 6x

since dx is very small

we have ,, as the final ans
4-6x

hope i could explain well..