Rate of Change

[flakine]

f(x)=(x+1)^2; x=a, x=a+h

Is this correct:

((a+h) +1)^2-(a+h)^2/((a+h)-a)
(a+h)^2+2(a+h)+1-(a+h)^2/h
2(a+h)+1/h
????

 

[pka]

It should be: (a+h)<SUP>2</SUP>+2(a+h)+1-(a+1)<SUP>2</SUP>/h.
That is, not (a+h) but (a+1).

 

[flakine]

My mistake!

How 'bout:

((a+h) +1)^2-(a+1)^2/(a+h)-a
a^2+2ah+h^2+2a+2h+1-a^2-2a-1/h
h(2a+h+2)/h
2a+h+2
???

 

[stapel]

The answer looks good to me.

Eliz.