/sci/ - Science & Math

[Math question need help No.6956973]

The question is 'make b the subject of the following formula: bc=bd+e

I can only seem to get

b=(bc-e)/d
And
b=(bd+e)/c

Wat am i doing wrong?

[Anonymous No.6956976]

>>6956973
>Wat am i doing wrong?
posting 7th grade homework on /sci/

[Anonymous No.6956982]

>>6956973
If you agree that
35 = 21 + 14,
do you also agree that
35 - 21 = 14?

[Anonymous No.6956985]

b should only be on one side of the equation. And now get back to trading Yu-gi-Oh cards with your peers, recess is almost over.

[Anonymous No.6956988]

bc = bd + e
bc - bd = e
b(c - d) = e
b = e / (c - d)

[Anonymous No.6956990]

>>6956973
I fucking joke that people post their middle school homework on here. This is actually middle school homework.

[Anonymous No.6956994]

>>6956990
You know, it's still better than all the popsci threads on consciousness or the singularity.

[Anonymous No.6956996]

Not sure if 11th grade is middle school. I'm in uk

[Anonymous No.6956997]

>>6956973
I really can't believe I'm about to do this, but okay:
<div class="math">bc-bd=b(c-d)=e</div>
Thus
<div class="math">b=\frac{e}{(c-d)}</div>

[Anonymous No.6957000]

>>6956994
>This pile of shit tastes a lot better than that rotten meat.

[Anonymous No.6957002]

>>6956996
You're in motherfucking year 11 and you can't do this? What set are you in?

[Anonymous No.6957005]

>>6957002
We dont have sets, there's like 30 in our year

[Anonymous No.6957011]

>>6957005
>We dont have sets
Well that might be the problem

>there's like 30 in our year
Where the hell are you? One of the isles?

[Anonymous No.6957012]

>>6956997
>>6956988
why do you guys want this kid to fail his homework?

fucking /sci/ assholes

[Anonymous No.6957017]

>>6957011
you may be surprised, but there are many in my maths class that are more retarded than me.

[Anonymous No.6957020]

sup /sci,
I dont post often but i just finished with a differential equations final and couldn't solve y''+16y=csc(4x). It's not homework, I'm just really curious about the form of the particular solution. Figured it would be more interesting than OP's problem.

[Anonymous No.6957022]

underage b&

[Anonymous No.6957024]

>>6957017
Im in texas so i can conferm this. Alot of people here in colege cant do this. And im in cal II.

[Anonymous No.6957026]

>>6957017
Believe me when I tell you I'm not, that's why sets are a good thing, they let weed out those that aren't capable and let those that are move forward. I wouldn't say that you're retarded, I only know you from this one question, but if you had been put into sets you'd have done this by now. Anyway these two:

>>6956997
>>6956988

are the right answers, in general you preform any operations you need to get the variables you want onto one side of the equals, then you try and isolate it. So in this case you subtract the <span class="math">bd[/spoiler] from one side and then factor out a <span class="math">b[/spoiler].

[Anonymous No.6957039]

>>6957020
bumping for any lurkers

[Anonymous No.6957046]

<span class="math">b=frac{muh}{diiiiick}=\text{8======D~~~}[/spoiler]

[Anonymous No.6957048]

<span class="math">b=frac{muh}{diiiiick}=8======D~~~[/spoiler]

[Anonymous No.6957057]

<span class="math">b=\frac{muh}{diiiiick}=\mathrm{8======D~~~}[/spoiler]

[Anonymous No.6957059]

>>6957020
Well it's auxiliary solution is: <div class="math">A\sin(4x)+B\cos(4x)</div> from that we can easily find it's Wronksian to be: <span class="math">W=-4[/spoiler] then it just a case of simplifying and integrating, that gives a particular solution of: <div class="math"> y_{p}=\sin(4x)\int \cos(4x)csc(4x) dx - \cos(4x)\int \sin(4x)csc(4x) dx </div> Now that integral looks tricky, and you might be right, but there'll be an identity you could use to simplify it.

>inb4 jsmath fail

[Anonymous No.6957087]

>>6957059
>That integral looks tricky
I kek'd

[Anonymous No.6957089]

>>6957059
Thanks, I used Asin(4x) + Bcos(4x) as the auxiliary solution but instead of finding W I found its second derivative then substituted into the original differential equation. This just lead to A and B both being equal to 0 so i was left with the complimentary solution. What exactly are you doing after finding the Wronskian?

[Anonymous No.6957103]

>>6957089
It's just the method of variation of parameters.

[Anonymous No.6957111]

>>6957103
Oh I see the -4 cancels out, thanks!