## nickymarden 3 years ago help.

1. nickymarden

2. nickymarden

the last equation is supposed to be f'(1)=

3. nickymarden

@amistre64

4. amistre64

after learning the derivative rules; you never go back to the limit definition ...

5. nickymarden

i knoow, but that's what he wants! ;/

6. amistre64

then plug in the (1+h) into the function and algebra it out; its simple enough with that function

7. amistre64

$\lim\frac{5-2(1+h)-(5-2(1))}{(1+h)-1}$

8. rs32623

well we have $f'(1)=\lim_{\Delta x \rightarrow 0}(f(1+\Delta x)-f(1))/\Delta x$ we have f(1+delta x)= 5-(2*(1+delta x)) =3-2*(delta x) & f(1)= 3 put these in above equation we have (3-2*(delta x)-3)/delta x delta x gets cancelled & we have -2 as answer..

9. nickymarden

yeeah, thanks. i got it :))

10. amistre64

good luck ;)