limit question.

[renegade05]

Hello there,

I am trying to solve this limit but keep getting stumped. Need someone to shine some light.

$\displaystyle \lim_{x \to 4}\left(\frac{-7x-16}{44x-11x^2} \ -\frac{1}{x-4}\right)$

I have tried factoring out a -11x out of the denominator of the first fraction and then multiplying everything out but it doesnt give the correct answer.

Please help.

Thanks.

 

[Deleted member 4993]

Hello there,

I am trying to solve this limit but keep getting stumped. Need someone to shine some light.

$\displaystyle \lim_{x \to 4}\left(\frac{-7x-16}{44x-11x^2} \ -\frac{1}{x-4}\right)$

$\displaystyle = \ \lim_{x \to 4}\left(\frac{-7x-16}{11x(4-x)} \ -\frac{1}{x-4}\right)$

$\displaystyle = \ \lim_{x \to 4}\left(\frac{(-7x-16) + 11x}{11x(4-x)} \ \right)$

$\displaystyle = \ \lim_{x \to 4}\left(\frac{4x-16}{11x(4-x)} \ \right)$

$\displaystyle = \ \lim_{x \to 4}\left(\frac{4(x-4)}{11x(4-x)} \ \right)$

$\displaystyle = \ - \ \lim_{x \to 4}\left(\frac{4}{11x} \ \right)$



I have tried factoring out a -11 out of the denominator of the first fraction and then multiplying everything out but it doesnt give the correct answer.

Please help.

Thanks.

 

[renegade05]

so the answer is $\displaystyle -\frac{1}{11}$

 

[Deleted member 4993]

so the answer is $\displaystyle -\frac{1}{11}$

You have doubt??? Why???

 

[renegade05]

so the answer is $\displaystyle -\frac{1}{11}$

You have doubt??? Why???

i am just confirming.

But my teacher said we can check our answers by using the nDeriv feature on our graphing calculator.

Can i not plug in nDeriv(Y1,x,4) where Y1 is the expression above and it pop out -1/11 (or close to).

When i plug it in it gives me .02272729.

I am new to all this so bare with me...