Help with C2 Differentiation question

Hello lovely internet people, can someone explain how you solve this question?

Tanks!

Hello lovely internet people, can someone explain how you solve this question?

Tanks!

You know that $f(x) = 3x^2 + 1$ so that $f(x + \delta x) = 3(x + \delta x)^2 + 1$. (i.e: wherever you see $x$, replace it with $x + \delta x$). Expand the square and write out all the terms.

i am confuse i don't quite understand the expand the y-coordinate bit :/ doesn't quite make sense to me..
@Kvothe the arcane @Zacken@Student403

Please do not tag so many people at the same time.

As you can see 3 separate people have gone through the effort of answering the same question and that is unnecessary time wasted.

EDIT: KtA has now deleted his answer having seen 2 other people answer the question, which just wastes his time.

You know that $f(x) = 3x^2 + 1$ so that $f(x + \delta x) = 3(x + \delta x)^2 + 1$. (i.e: wherever you see $x$, replace it with $x + \delta x$). Expand the square and write out all the terms.

How do you do the next part?

sorry