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Mathematics 15 Online
OpenStudy (anonymous):

Factor x^2-x-1?

OpenStudy (anonymous):

go get 'em myininaya!

OpenStudy (anonymous):

still working?

myininaya (myininaya):

\[b=(\frac{-1}{2}+z)+(\frac{-1}{2}-z)\] \[a*c=-1=(\frac{-1}{2}+z)(\frac{-1}{2}-z)=\frac{1}{4}-z^2=>z^2=\frac{1}{4}-ac=>z=\pm \sqrt{\frac{1}{4}-ac}\] replace bx with \[bx=(\frac{-1}{2}+\sqrt{\frac{1}{4}-ac})x+(\frac{-1}{2}-\sqrt{\frac{1}{4}-ac})x\] so we have \[x^2+(\frac{-1}{2}+\sqrt{\frac{1}{4}-ac})x+(\frac{-1}{2}-\sqrt{\frac{1}{4}-ac})x-1\] but ac=-1 \[x^2+(\frac{-1}{2}+\sqrt{\frac{1}{4}-(-1)})x+(\frac{-1}{2}-\sqrt{\frac{1}{4}-(-1)})x-1\] \[x^2+(\frac{-1}{2}+\sqrt{\frac{1+4}{4}})x+(\frac{-1}{2}-\sqrt{\frac{1+4}{4}})x-1\] \[x^2+(\frac{-1+\sqrt{5}}{2})x+(\frac{-1-\sqrt{5}}{2})x-1\] \[x(x+\frac{-1+\sqrt{5}}{2})+\frac{-1-\sqrt{5}}{2}(x-\frac{2}{-1-\sqrt{5}})\] \[x(x+\frac{-1+\sqrt{5}}{2})+\frac{-1-\sqrt{5}}{2}(x+\frac{2}{1+\sqrt{5}}*\frac{1-\sqrt{5}}{1-\sqrt{5}})\] \[x(x+\frac{-1+\sqrt{5}}{2})+\frac{-1-\sqrt{5}}{2}(x+\frac{2(1-\sqrt{5})}{1-5})\] \[x(x+\frac{-1+\sqrt{5}}{2})+\frac{-1-\sqrt{5}}{2}(x-\frac{1-\sqrt{5}}{2})\] \[x(x+\frac{-1+\sqrt{5}}{2})+\frac{-1-\sqrt{5}}{2}(x+\frac{-1+\sqrt{5}}{2})\] \[(x+\frac{-1+\sqrt{5}}{2})(x+\frac{-1-\sqrt{5}}{2})\]

OpenStudy (anonymous):

Wow. I believe you since when this equation = 0, x = \[\left( 1\pm \sqrt{5} \right) \div2\]. Impressive!

myininaya (myininaya):

lol

OpenStudy (anonymous):

are you out of your mind?

myininaya (myininaya):

he said impressive

OpenStudy (anonymous):

impressed with how long to took to get \[x=\frac{1\pm\sqrt{5}}

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