Okie . i never did delta so.. i definitly need help?

Question

Find f(x + deltax) for f(x) = x^2 -2x - 3

Answer 1

Use dx instead of deltax:

Everywhere you see an x, write (x + dx)

f(x + dx) = (x + dx)^2 - 2(x + dx) - 3

x^2 + 2dx + (dx)^2 - 2x - 2dx - 3

x^2 + (dx)^2 - 2x - 3

Hope that helps!