# Thread: Lots Of Help Please!! Asap!

1. ## Lots Of Help Please!! Asap!

hi i need help with these asap

1.
If , then is continuous at

Choice

0

everywhere

2.
The equation
implicitly defines as a function of . Find .

3.

is discontinuous at ____ because _________________
(More than one selection may be correct. Keep in mind that if a function tends to infinity as , the limit does not exist at .)
Choice
because does not exist.
because does not exist.
because does not exist.
because does not exist.
because
Number of available correct choices: 2

4.

If ,
then we have

(Select the correct statement(s).)

Choice
f is both continuous and differentiable at x = 0
f '(x) exists for all x except x = 0 f is not continuous at x = 0
f '(x) is continuous for all x
f '(x) does not exist anywhere
f '(x) exists for all x but is not continuous for all x
f is continuous at x = 0 but not differentiable at x = 0
Number of available correct choices: 2

5.

Above is the graph of a function . Sketch the graph of ?
6.

If ,
then at 0, is??

7.

Find if .

8.

. Select the intervals on which the function is continuous.
Choice

Number of available correct choices: 3

2. Originally Posted by chousta
hi i need help with these asap

1.
If , then is continuous at

Choice

0

everywhere

2.
The equation

implicitly defines as a function of . Find .

3.

is discontinuous at ____ because _________________
(More than one selection may be correct. Keep in mind that if a function tends to infinity as , the limit does not exist at .)
Choice
because does not exist.
because does not exist.
because does not exist.
because does not exist.
because
Number of available correct choices: 2

4.

If ,
then we have

(Select the correct statement(s).)

Choice
f is both continuous and differentiable at x = 0
f '(x) exists for all x except x = 0 f is not continuous at x = 0
f '(x) is continuous for all x
f '(x) does not exist anywhere
f '(x) exists for all x but is not continuous for all x
f is continuous at x = 0 but not differentiable at x = 0
Number of available correct choices: 2

5.

Above is the graph of a function . Sketch the graph of ?
6.

If ,
then at 0, is??

7.

Find if .

8.

. Select the intervals on which the function is continuous.
Choice

Number of available correct choices: 3
Is this a test?

I will do ONE until you say it is not

8. $\displaystyle y=\tan\bigg(\frac{1}{(x+1)^4}\bigg)$

So $\displaystyle arctan(y)=\frac{1}{(x+1)^4}$

Differentiating we get $\displaystyle \frac{y'}{1+y^2}=\frac{-4}{(x+1)^5}$

Seeing that $\displaystyle y=\tan\bigg(\frac{1}{(x+1)^4}\bigg)$

wee see that $\displaystyle y'=\frac{-4\bigg[1+\tan^2\bigg(\frac{1}{(x+1)^4}\bigg)\bigg]}{(x+1)^5}$

3. ## No

Hi.

no its not a test. out of a multiple choice worksheet with no answers. and i have an exam very very soon and im freaking out.

4. Hello, chousta!

2) The equation: .$\displaystyle -4xy - \frac{2}{xy} - \frac{2}{x^2y^2} \:=\:-6$ .implicitly defines $\displaystyle y$ as a function of $\displaystyle x.$
Find $\displaystyle \frac{dy}{dx}$
Multiply by -1: . $\displaystyle 4xy + 2x^{-1}y^{-1} + 2x^{-2}y^{-2} \;=\;6$

Differentiate implicitly: . $\displaystyle 4x\frac{dy}{dx} + 4y - 2x^{-1}y^{-2}\frac{dy}{dx} - 2x^{-2}y^{-1} - 4x^{-2}y^{-3}\frac{dy}{dx} - 4x^{-3}y^{-2} \;=\;0$

Rearrange terms: . $\displaystyle 4x\frac{dy}{dx} - \frac{2}{xy^2}\frac{dy}{dx} - \frac{4}{x^2y^3}\frac{dy}{dx}\;=\;-4y + \frac{2}{x^2y} + \frac{4}{x^3y^2}$

Multiply by $\displaystyle \frac{x^3y^3}{2}\!:\quad 2x^4y^3\frac{dy}{dx} - x^2y\frac{dy}{dx} - 2x\frac{dy}{dx} \:=\:-2x^3y^4 + xy^2 + 2y$

Factor: . $\displaystyle x(2x^3y^3 - xy - 2)\frac{dy}{dx} \;=\;\text{-}y(2x^3y^3 - xy - 2)$

Therefore: . $\displaystyle \frac{dy}{dx}\;=\; \frac{\text{-}y(2x^3y^3 - xy - 2)}{x(2x^3y^3 - xy - 2)} \;=\;\boxed{-\frac{y}{x}}$

5. Originally Posted by chousta
Hi.

no its not a test. out of a multiple choice worksheet with no answers. and i have an exam very very soon and im freaking out.
For number five use the fact that mins and maxs for f(x) are zeros for f'(x)

1.its everywhere

2. you will just have to grunt implicitly differentiate

3. $\displaystyle \ln(u(x))$ is undefined $\displaystyle \forall{x}\leq{0}$

4. if f(x) is continous at c then

$\displaystyle \lim_{x\to{c}}f(x)=f(c)$

and if it is differentiable at c then

$\displaystyle \lim_{x\to{c}}f'(x)=f'(c)$

6. if it is talking about continuity check out the first part of the last thing I said

7. done

8.check vert. asymptotes (places that make denominator equal to 0)

6. ## Thank U

Thank you all so much.
but i still dont get wat the answer for 3 and 5 are. ESP 5?? how would i graph that? what is the process.

thank you all so much.im hopin i pass this test!

7. Originally Posted by chousta
[snip]
5.

Above is the graph of a function . Sketch the graph of ?
[snip]
Pretend it's the graph of y = sin x. Then df/dx = cos x.

Alternatively, recall that df/dx gives the gradient of the tangent at each point of the curve .....