Question

find & simplify the difference quotient
[f(x+h)-f(x)]/ h, where h cannot = 0
for the given funtion: f(x)=2x^2+4x+3

Answer 1

this is 2(x+h)^2+4(x+h) +3 - (2x^2+4x+3)
--------------------------------
h

Answer 2

yes, I realise that.. but after I group and simplify, I end up with h=-2
but that's not the answer in my textbook, I'm not sure where I went wrong:/

Answer 3

i don't quite understand what u want here - this function produces the derivative of the f(x) when h --> 0 i.e. limit of it as h---> 0 . its not about finding a value of h

Answer 4

well the answer is apparently, 2x +h + 6
and I don't understand how to get this

Answer 5

the answer should be 4x + 4 + h

Answer 6

2(x+h)^2+4(x+h) +3 - (2x^2+4x+3)
= 2x^2 + 4xh + 2h^2 + 4x + 4h + 3 - 2x^2 - 4x - 3
= 4xh + + 4h + 2h^2

dividing this by h gives 4x + 4 + 2h

- i was wrong in my last post

Answer 7

but that's still not the answer I was given.. is it wrong then?

Answer 8

turns out the ansser given is wrong, thanks :)

Answer 9

**answer