hello all,

question:

$\displaystyle f(x)=1/x $ evaluate $\displaystyle f(x)-f(a)/x-a$

thank you

Printable View

- Oct 1st 2009, 03:51 AMstr33tl0rdpre-calculus/functions help
hello all,

question:

$\displaystyle f(x)=1/x $ evaluate $\displaystyle f(x)-f(a)/x-a$

thank you - Oct 1st 2009, 06:05 AMialbrekht
$\displaystyle f(x)-f(a)/x-a = 1/x-(1/a)*(1/x)-a = f(x)(1-1/a)-a$

or you can write it as

$\displaystyle f(x)-f(a)/x-a = 1/x-(1/a)*(1/x)-a = (a-1)/(a*x)-a$ - Oct 1st 2009, 06:06 AMVonNemo19
- Oct 1st 2009, 05:08 PMstr33tl0rd
thank you for the help guy, but it seems like that wasn't the answer =|

i think i have miswritten the question, i'll retry:

if $\displaystyle f(x)=1/x$

evaluate

$\displaystyle [f(x)-f(a)]/(x-a)$

and the answer is supposed to be: $\displaystyle -1/ax$

i need a working out, thank you very much all you guys and girls (Wink) - Oct 1st 2009, 05:30 PMskeeter
- Oct 1st 2009, 05:51 PMstr33tl0rd
thank you, thats the step i got up to:

$\displaystyle

\frac{\frac{a-x}{ax}}{x-a}

$

and i continued as follows, correct me if i am wrong:

$\displaystyle \frac{a-x}{ax*(x-a)}$

expanding:

$\displaystyle \frac{a-x}{ax(sqr)-a(sqr)x}$

and here is where i get stuck, don't know how to continue or simply that, thanks again - Oct 1st 2009, 05:54 PMskeeter
- Oct 1st 2009, 05:58 PMstr33tl0rd
thank you very much...(Rock)