can u please help me answer this question and also please wr

can u please help me answer this question and also please write clearly so I can understand thank you so much

Given f(x) = 3x2-x, Evaluate f(x + h) - f(x)

Solution

Given

f(x) = 3x^2 – x

f(x+h) = 3(x+h)^2 – (x+h) = 3x^2 + 3h^2 + 6xh – x – h

Now f(x+h) – f(x) = 3x^2 + 3h^2 + 6xh – x – h – 3x^2 + x = 3h^2 + 6xh – h

And

[f(x+h) – f(x)]/h = 3h + 6x - 1