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Mathematics 19 Online
Parth (parthkohli):

Nice problem with a nice solution.

OpenStudy (here_to_help15):

Yes the problem is?

Parth (parthkohli):

Solve\[\alpha + \beta + \gamma=0\]\[\alpha \beta + \beta \gamma + \alpha \gamma = 0\]\[\alpha\beta\gamma = 0\]

OpenStudy (inkyvoyd):

isn't that the cubic?

OpenStudy (here_to_help15):

your white too :D who was white first???

Parth (parthkohli):

inky

Parth (parthkohli):

btw, inky is asian.

OpenStudy (inkyvoyd):

I'm not white, i'm invisible. There is a difference

OpenStudy (here_to_help15):

lol i wasn't tlking about skin lol

OpenStudy (perl):

x^3 + ( a + b + c)*x^3 + (ab + ac + bc)*x + abc

OpenStudy (here_to_help15):

hm thats why i put this because i was invisible

Parth (parthkohli):

Bye guys, perl has done it.

OpenStudy (bibby):

sad

OpenStudy (anonymous):

More problems please bro @ParthKohli

OpenStudy (inkyvoyd):

now @Here_to_Help15 , I'm invisible. You are white. Check our profile pics. THere is a difference

OpenStudy (callisto):

@perl Explain, explain pleaseeeeee~~~

OpenStudy (inkyvoyd):

(x-a)(x-b)(x-c) callisto

OpenStudy (inkyvoyd):

http://en.wikipedia.org/wiki/Vieta%27s_formulas @Callisto

OpenStudy (inkyvoyd):

at least I think @ParthKohli am i rite

Parth (parthkohli):

Yup.

OpenStudy (callisto):

Still confused. Btw, it would be x^3 + ( a + b + c)*x^2 + (ab + ac + bc)*x + abc then

Parth (parthkohli):

That'd reduce our cubic to \(p(x) = x^3\) aaaaaaaaand.

OpenStudy (inkyvoyd):

hahha you caught the two calliso :3

Parth (parthkohli):

The only possible value of \(\alpha, \beta , \gamma\) is 0. Therefore \(\alpha = \beta = \gamma = 0\)

OpenStudy (callisto):

This is not nice.. This is trivial...

OpenStudy (inkyvoyd):

lol @Callisto yearn for @foolformath problems?

Parth (parthkohli):

Posting one foolish problem right away.

OpenStudy (perl):

the solutions to a+b+c = m ab +ac + bc = p abc =q are the same as the roots to x^3 + p*x^2 +q*x + c = 0

OpenStudy (perl):

and since m=0 , p = 0 , q = 0 we have , the solutions are the roots of x^3 + 0*x^2 + 0*x + 0 = 0 x^3 = 0 x = 0 so the only solution is zero

OpenStudy (perl):

typo *

OpenStudy (callisto):

That's clear, thanks! :)

OpenStudy (perl):

the solutions to a+b+c = m ab +ac + bc = p abc =q are the same as the roots of x^3 + m*x^2 +p*x + q = 0

Parth (parthkohli):

\[x^3 - mx^2 + px - q = 0\]

OpenStudy (callisto):

I got your idea :)

OpenStudy (perl):

oh good point, the sign alternates

OpenStudy (callisto):

Idea matters LOL I was wondering why the solutions to a+b+c = m ab +ac + bc = p abc =q are the same as the roots to x^3 + p*x^2 +q*x + c = 0 But I understand it now. Thanks!

OpenStudy (perl):

yes, i had to think about it :)

OpenStudy (callisto):

For recap later: Solve: a + b + c = 0 ab + bc + ac = 0 abc = 0 Let a, b, c be the roots of a cubic equation in unknown x. Then we have (x-a)(x-b)(x-c) = 0. Consider (x-a)(x-b)(x-c) = 0, expand the left side, we get \(x^3 - (a+b+c)x^2 + (ab + bc + ac)x - abc = 0\) Substitute the values of the given equations into this polynomial equation, we have \( x^3 = 0\) Hence, we have x = 0 as the only solution. Therefore, we only have the trivial solution a = b = c = 0 to the given system.

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