Does anyone know the reason behind this. G vector = k * u vector ((I'm just guessing, but is the linear relationship an imaginary thing where if two numbers increase or decrease with each other with a difference in value, we say that there is a fixed number a constant that makes the two numbers equal))

and I also asked a question about derivation in Quora, and no one answered it.

Can you explain to me why the power rule and the Derivation formula gave a different result?

2) Why Derivation formula did not work but power rule did work? F(x) =x^2-2x . (x+h) ^2 -2(x+h) - x^2 -2x) /h = after simplifying it become h (2x+h-2)-4x/h = 2x-4x+h-2 =-2x-2 .but the power rule for x^2-2x is 2x-2 .why did I not get the same result