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Mathematics 20 Online
OpenStudy (anonymous):

Dany612

OpenStudy (anonymous):

present!

OpenStudy (anonymous):

\[\sqrt{2x-3}\]

OpenStudy (anonymous):

this is the problem?

OpenStudy (anonymous):

you forgot the outside x

OpenStudy (anonymous):

oh ok.. \[x \sqrt{2x-3}\]

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

We need product rule and chain rule here.

OpenStudy (anonymous):

\[(x)(\sqrt{2x-3})\prime + (1)(\sqrt{2x-3})\]

OpenStudy (anonymous):

Ok that is product rule.. now we need chain rule to find the derivative of \[\sqrt{2x-3}\]

OpenStudy (anonymous):

f(x) = sqrt(x) g(x) = 2x-3

OpenStudy (anonymous):

so the derivative of \[\sqrt{2x-3}\] is \[\frac{1}{2\sqrt{2x-3}}* 2\]

OpenStudy (anonymous):

Which is \[\frac{2}{2\sqrt{2x-3}}\] or \[\frac{1}{\sqrt{2x-3}}\] because the 2's cancel

OpenStudy (anonymous):

so now the derivative will look like combining the chain and product rule.\[(x)(\frac{1}{\sqrt{2x-3}}) + \sqrt{2x-3}\] or \[\frac{x}{\sqrt{2x-3}}+ \sqrt{2x-3}\]

OpenStudy (anonymous):

You can leave it like this or find a common denominator.

OpenStudy (anonymous):

okay

OpenStudy (anonymous):

Finding a common denominator is probably best so the common denominator is \[\sqrt{2x-3}\] so you do \[\frac{x}{\sqrt{2x-3}} + \frac{\sqrt{2x-3}}{1}*\frac{\sqrt{2x-3}}{\sqrt{2x-3}}\]

OpenStudy (anonymous):

so you are left with \[\frac{x + 2x-3}{\sqrt{2x-3}}\] or \[\frac{3x - 3}{\sqrt{2x-3}}\]you can factor out a 3 in the numerator so the final answer is \[\frac{3(x-1)}{\sqrt{2x-3}}\]

OpenStudy (anonymous):

Anything you dont understand?

OpenStudy (anonymous):

not yet

OpenStudy (anonymous):

Cool.

OpenStudy (anonymous):

okay I know I should know this but the multiplying by the donimator, i need more elaboration on that.

OpenStudy (anonymous):

ok you have \[\frac{x}{\sqrt{2x-3}} + \frac{\sqrt{2x-3}}{1}\]

OpenStudy (anonymous):

in order to add fractions you need a common denominator.

OpenStudy (anonymous):

Common denominator in this case is \[(\sqrt{2x-3})(1) = \sqrt{2x-3}\]

OpenStudy (anonymous):

so you multiply any fraction that doesnt have \[\sqrt{2x-3}\] in the denominator.

OpenStudy (anonymous):

By \[\frac{\sqrt{2x-3}}{\sqrt{2x-3}}\]

OpenStudy (anonymous):

oh wait nvm, i got it

OpenStudy (anonymous):

The first fraction already has \[\sqrt{2x-3}\] in the denominator so no need to multiply anything to it.. The second fraction on the other hand has a 1 in the denominator.. But we need sqrt(2x-3) in the denominator.. so we multiply the second fraction by (sqrt(2x-3))/(sqrt(2x-3)).. like this \[\frac{x}{\sqrt{2x-3}} + \frac{\sqrt{2x-3}}{1}*\frac{\sqrt{2x-3}}{\sqrt{2x-3}}\]

OpenStudy (anonymous):

You understand now??

OpenStudy (anonymous):

Yeah I did, sorry for making you right that whole thing.

OpenStudy (anonymous):

Its alright.

OpenStudy (anonymous):

okay so thats all the hlep I needed. Thanks!

OpenStudy (anonymous):

No problem.. Im suprised i got it right due to the fact that im tired lol..

OpenStudy (anonymous):

lol how come?

OpenStudy (anonymous):

Lol i have no idea.. I havent done much today lol.. Just played MW3

OpenStudy (anonymous):

lol I bet its all that hard concentration on killing enemies hah

OpenStudy (anonymous):

lol or raging one of the two haha

OpenStudy (anonymous):

I wonder if I'll enjoy those benifits lol because I haven't played MW3 yet or have plans to buy it.

OpenStudy (anonymous):

Lol its pretty fun, i like the first person shooter games though.. even though im not all that good at them haha

OpenStudy (anonymous):

Yeah same here, but I fear of being addicted.

OpenStudy (anonymous):

do you mind lending a hand on another problem just like this one. for some reason I got it wrong.

OpenStudy (anonymous):

lol i know!!! Im going to have to resist playing so i can do my hw lol

OpenStudy (anonymous):

and yeah i can help

OpenStudy (anonymous):

x(1-2x)^3

OpenStudy (anonymous):

i wonder where i messed up

OpenStudy (anonymous):

Ok we need product rule and chain rule again.

OpenStudy (anonymous):

Product rule:\[(x)((1-2x)^3)\prime + (1-2x)^3\]

OpenStudy (anonymous):

ok so far so good

OpenStudy (anonymous):

i skipped the derivative of "x" on the right side of the plus sign because it is 1.

OpenStudy (anonymous):

And something X 1 is something.

OpenStudy (anonymous):

ok now we need chain rule for \[(1-2x)^3\]

OpenStudy (anonymous):

f(x) = x^3 g(x) = 1-2x So the derivative is\[2(1-2x)^2*(-2)\]

OpenStudy (anonymous):

wait why is the coefficient 2 instead of 3?

OpenStudy (anonymous):

Now combine chain rule and product rule\[x*2(1-2x)^2*(-2) + (1-2x)^3 \]

OpenStudy (anonymous):

Because you have to use power rule.

OpenStudy (anonymous):

power rule says \[f(x) = x^{n}\] then \[f \prime (x) = nx^{n-1}\]

OpenStudy (anonymous):

i know but x^3 is 3x^2 so 3(1-2x)^2??

OpenStudy (anonymous):

you dont have the same n

OpenStudy (anonymous):

oh i made a type-o

OpenStudy (anonymous):

no wonder you're confused lol

OpenStudy (anonymous):

yeah I know my product rule lol

OpenStudy (anonymous):

it should be \[x * 3(1-2x)^2 * (-2) + (1-2x)^3\]

OpenStudy (anonymous):

okay thats exactly what I got, now to simplify

OpenStudy (anonymous):

ok we can factor out at \[(1-2x)^2\]

OpenStudy (anonymous):

\[(1-2x)^2[x * 3 + 1 - 2x]\]

OpenStudy (anonymous):

so the derivative should be \[(1-2x)^2[x + 1]\]

OpenStudy (anonymous):

let me see if that is correct.

OpenStudy (anonymous):

hold on what happened to your -2?

OpenStudy (anonymous):

i have -6x(1-2x)^2+(1-2x)^3

OpenStudy (anonymous):

And i forgot the -2

OpenStudy (anonymous):

see im tired lol.. let me fix it lol

OpenStudy (anonymous):

\[(1-2x)^2[-6x + 1 - 2x]\]

OpenStudy (anonymous):

yes thats what i got

OpenStudy (anonymous):

which is \[(1-2x)^2[-8x + 1]\] then factor out a -1 so the x term in the parenthesis is positive.. \[-(1-2x)^2[8x-1]\]

OpenStudy (anonymous):

And that is correct.. woohoo xD

OpenStudy (anonymous):

yes, I see what my problem was. I forgot to add join the commons together which were -6 and -2 xD omg I'm such a fail.

OpenStudy (anonymous):

-6x and -2x*

OpenStudy (anonymous):

Ahh so you did it right but added wrong.. i do that too so dont feel bad lol

OpenStudy (anonymous):

haha yeah simple mistkes. well thanks Tyler! Your awesome and a life saver!. sorry for bothering you when you felt lazy lol

OpenStudy (anonymous):

i mean tired

OpenStudy (anonymous):

lol not a problem!! If you have anymore questions dont be afraid to ask!!

OpenStudy (anonymous):

no thats it. I finished up my 20 hw problems. I do have another question but ill ask you on facebook bec i gotta switch computers.

OpenStudy (anonymous):

oh ok

OpenStudy (anonymous):

wait are u still here, i just switched computers

OpenStudy (anonymous):

yeah

OpenStudy (anonymous):

so your studying computer engineering right?

OpenStudy (anonymous):

yeah

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