## refusetofail 3 years ago 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

1. cwrw238

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

2. refusetofail

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:/

3. cwrw238

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

4. ksaimouli

|dw:1353883607543:dw|

5. refusetofail

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

6. cwrw238

the answer should be 4x + 4 + h

7. cwrw238

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

8. refusetofail

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

9. refusetofail

turns out the ansser given is wrong, thanks :)

10. refusetofail