## anonymous one year ago This may just be a forgetful moment on my part, but could someone please explain to me how you get...

1. anonymous

$f(x)=3x^2+2$ from $3x^2+3x \Delta x+ \Delta x^2+2$ by substituting the limit (0) into the equation?

2. anonymous

I'm learning derivatives if that helps explain anything.

3. ZeHanz

The limit means $$\Delta x$$ becomes smalles and smaller. Now, 3x has a certain value, once you have chosen the x. Imagine what happens with the term $$3x \cdot \Delta x$$: you have to multiply this certain value of 3x with an ever smaller number: it becoms vanishingly small, in fact it goes to 0. Same happens to $$(\Delta x)^2$$, leaving you with $$3x^2 + 2$$.

4. anonymous

So only the $x \Delta$ will be substituted with the 0, correct?

5. amistre64

yes

6. anonymous

Is there a particular reason why? (sorry, but if i know why it helps me remember to do it)

7. anonymous

Oops! Never mind! I see now. Thank you.

8. ZeHanz

yw!