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Mathematics 11 Online
OpenStudy (anonymous):

if

OpenStudy (anonymous):

IF you can keep your head when all about you. Are losing theirs and blaming it on you, If you can trust yourself when all men doubt you, But make ...

OpenStudy (anonymous):

\[a,b,c \]are roots of the equation\[x^3-x-1=0\] compute \[\frac{ 1-a }{ 1+a }+\frac{ 1-b }{ 1+b }+\frac{ 1-c }{ 1+c}\]

OpenStudy (anonymous):

simplified \[\frac{ 1 }{ a+1 }+\frac{ 1 }{ b+1 }+\frac{ 1 }{ c+1 }-3\] note\[a^3=a+1,b^3=b+1,c^3=c+1\]

OpenStudy (anonymous):

so\[\frac{ 1 }{ a^3 }+\frac{ 1 }{ b^3 }+\frac{ 1 }{ c^3 }-3\]

OpenStudy (anonymous):

if we divide by a,b,c\[1-\frac{ 1 }{ a^2 }=\frac{ 1 }{ a^3 }\]

OpenStudy (anonymous):

\[[3-(\frac{ 1 }{ a^2 }+\frac{ 1 }{ b^2 }+\frac{ 1 }{ c^2 })]-3\]

OpenStudy (anonymous):

\[(x-a)(x-b)(x-c)=x^3-x^2(a+b+c)+x(bc+ab+ac)-(abc)\] coefeecients of x^2 is 0 x is -1 and constant 0 so\[a+b+c=0,bc+ab+ac=-1,abc=1\]

OpenStudy (anonymous):

\[\frac{ (ac)^2+(bc)^2+(ab)^2}{ (abc)^2 }\] we need to get this with all the info

OpenStudy (anonymous):

\[(x+y+z)^2=x^2+y^2+z^2+2(xy+yz+zx)\]

OpenStudy (anonymous):

\[(0)^2=(ab)^2+(bc)^2+(ca)^2+2(-1)\] \[(ab)^2+(bc)^2+(ca)^2=2\]

OpenStudy (anonymous):

so the answer to\[[3-(\frac{ (ab)^2(bc)^2+(ca))^2 }{ (abc)^2 })]-3=[3-\frac{ 2 }{ 1 }]-3=-2\]

OpenStudy (anonymous):

wat doyou think guys,please help

OpenStudy (anonymous):

Actually the answer is 1 So you are not correct

OpenStudy (anonymous):

how can we find the answer 1

OpenStudy (anonymous):

\[\frac{ 1-a }{ 1+a }+\frac{ 1-b }{ 1+b }+\frac{ 1-c }{ 1+c }\] \[-1+\frac{ 2 }{ 1+a }-1+\frac{ 2 }{ 1+b }-1+\frac{ 2 }{ 1+c }\] \[2(\frac{ 1 }{ 1+a }+\frac{ 1 }{ 1+b }+\frac{ 1 }{ 1+c })-3\] \[2(\frac{ (1+b)(1+c)+(1+a)(1+c)+(1+a)(1+b) }{ (1+a)(1+b)(1+c) })-3\] \[2(\frac{ (ab+ac+bc)+2(a+b+c)+3 }{ abc+(ab+ac+bc)+(a+b+c)+1 })-3\]Now insert the respective values so as to get the ANSWER 1

OpenStudy (anonymous):

i am out of medals...thanks

OpenStudy (anonymous):

Multiply it out directly: -> 3 + (a + b + c) - (ab +bc + ca) - 3abc / (a+1)(b+1)(c+1) -> 3 + (a + b + c) - (ab +bc + ca) - 3abc / a^3b^3c^3 = 3 +1 - 3 /1 = 1

OpenStudy (anonymous):

i really went for miles to show a centimeter journey

OpenStudy (anonymous):

Now and again, it is just a question of doing the first thing that comes to mind....:-)

OpenStudy (unklerhaukus):

\[x^3−x−1=0\] 1 is not a solution as \[1^3−1−1=1\neq0\]

OpenStudy (anonymous):

We are not finding solutions, we are evaluating the expression in the top post...

OpenStudy (unklerhaukus):

to hard for me

OpenStudy (anonymous):

is it possible to getthe values ofa,b,c

OpenStudy (anonymous):

Do you mean by hand?

OpenStudy (anonymous):

http://en.wikipedia.org/wiki/Plastic_number

OpenStudy (anonymous):

very helpful,i asked this becuause 1 was looking for the solution of the cube

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