#evaluate if m is natural

1 messages · Page 1 of 1 (latest)

knotty perch
#

oh boy

#

$x^m=k$

sour dockBOT
knotty perch
#

$\int(\sqrt[m]{(k^{3m}+k^{2m}+k^m)(2k^2+3k+6)})dx$

sour dockBOT
knotty perch
#

Agh I'm too lazy to multiply that

#

yeah

#

hmm how?

#

mhm

#

Yes I did

#

That's why you have $k^{3m}+k^{2m}+k^m$

sour dockBOT
knotty perch
#

I've defined k as $x^m$

sour dockBOT
knotty perch
#

Why not?

#

$k^{3m} = x^{m^{3m}}$

sour dockBOT
knotty perch
#

So when you get $x^{3m}$ inside the root it becomes $(x^{3m})^m$

sour dockBOT
knotty perch
#

So that's basically $(x^m)^{3m}$

sour dockBOT
knotty perch
#

Mhm, yes

#

So that's just k$^{3m}$

sour dockBOT
knotty perch
#

You simplify this

#

and then the idea is that you can effectively remove the root

#

You won't need substitution

#

One sec, I'll remove the root

#

Yes, but when we remove the root you'll get x

#

I'm too lazy to simplify it so let me get wolfram

#

see, doing that by hand is pain

#

just...pain

knotty perch
#

so

#

If you're taking the mth root of this you're effectively removing that exponent

#

So you can just replace k with x

#

Mhm

#

basically, $\sqrt[m]{k^{m+1}}=\sqrt[m]{x^{m(m+1)}}$

sour dockBOT
knotty perch
#

m and m cancel each other

#

you get x^m+1

#

Basically, we have replaced k with x by taking the root

#

sure

knotty perch
#

Right

#

Sorry, went offline

#

Let's do this step-by-step

#

$3k^{m+1}+2k^{m+2}+3k^{2m+1}+2k^{2m+2}+3k^{3m+1}+2k^{3m+2}+6k^{3m}+6k^{2m}+6k^m$

sour dockBOT
knotty perch
#

now

#

let's substitute k with its definition

#

x^m

#

$3(x^m)^{m+1}+2(x^m)^{m+2}+3(x^m)^{2m+1}+2(x^m)^{2m+2}+3(x^m)^{3m+1}+2(x^m)^{3m+2}+6(x^m)^{3m}+6(x^m)^{2m}+6(x^m)^m$

sour dockBOT
knotty perch
#

yeah?

#

Now, using the laws of exponents, we can multiply the exponents in each term

#

or

#

Let's take x^m as the common term

#

nvm

#

$3x^{m(m+1)}+2x^{m(m+2)}+3x^{m(2m+1)}+2x^{m(2m+2)}+3x^{m(3m+1)}+2x^{m(3m+2)}+6x^{m(3m)}+6x^{m(2m)}+6x^{m(m)}$

sour dockBOT
knotty perch
#

Yeah?

#

we've just multiplied the exponents

#

Pretty much, yea

#

Except, I've combined m with the other exponents

#

basically $(x^k)^m=x^{km}$

sour dockBOT
knotty perch
#

I've used that here

#

ok so

knotty perch
#

wait..

#

Ah it's addition

#

You can't really distribute it like that

#

yeah, took me a while

#

I suppose you can sub it with dk

#

well, if n is natural x^m should be differentiable, right?

#

Well if you wanna know

knotty perch
#

Oh what's it?

#

$2x^{2m^2}+3x^{m^2}+6^m$

sour dockBOT
knotty perch
#

6x^m

#

The entire expression?

#

Ah right sorry

#

$2x^{3m}+3x^{2m}+6x^m$

sour dockBOT
knotty perch
#

So did you get t?

#

Ah fair enough

#

Damn, I can't believe I didn't see that

#

not seeing these steps is gonna kill my math skills

#

But yeah, tons of practice is required

#

$\frac{sin^6x + cos^6x}{sin^2x+cos^2x}$?

sour dockBOT
knotty perch
#

Ah right

sour dockBOT
#

meckron

knotty perch
#

$(sin^4x+sin^2xcos^2x+cos^4x)(\frac{1}{sin^2x}+\frac{1}{cos^2x})
= (sin^2x+cos^2x+cot^2xsin^2x)+(cos^2x+sin^2x+tan^2xcos^2x)$

sour dockBOT
knotty perch
#

Without subbing?

#

oh that's gonna kill me

#

sorry, never took an integrals course

#

yet

#

$\frac{1-3sin^2xcos^2x}{sin^2xcos^2x}=\frac{1}{sin^2xcos^2x}-3\ \int{k} = \int{sec^2xcsc^2x}dx - 3x = tanx+cotx-3x+C$

sour dockBOT
knotty perch
#

smth like that?

#

can't get it, brain's dead rn

#

How do you make the numerator a perfect square there?

#

right