If you do not know what "gradient' (American English: "slope") of a line is, you should not be attempting a problem like this. Finding the derivative is far more advanced that the 'slope' or 'gradient' of a line.
i guess basic for u but im trying to know all these things sir
I don't think you're quite ready for derivatives and calculus, especially since you've been posting elementary algebra questions. You need to be proficient in algebra to do well in calculus.