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Mathematics 14 Online
OpenStudy (anonymous):

Solve x2 + 7x = 1

OpenStudy (anonymous):

oh look just another quadratic equation

OpenStudy (anonymous):

this one does not factor, so you really do have to use the quadratic formula subtract \(1\) to get \[x^2+7x-1=0\] then find \[\frac{-b\pm\sqrt{b^2-4ac}}{2a}\] with \[a=1,b=7,c=-1\]

OpenStudy (anonymous):

you want to try it yourself? you still need help? you just want the answer?

OpenStudy (anonymous):

yeah yeah yeah ))):

OpenStudy (anonymous):

of course i don't just want the answer hhaaha, ill try

OpenStudy (anonymous):

k i will check if you like gonna go get a peach or something

OpenStudy (anonymous):

-7 +/- sqrt 45/2

OpenStudy (anonymous):

is how far i got

OpenStudy (anonymous):

close

OpenStudy (anonymous):

im not sure how to finish it

OpenStudy (anonymous):

well it would in fact be finished there but you made a very common sign error lets do that part right

OpenStudy (anonymous):

oh is the 7 positive

OpenStudy (anonymous):

inside the radical is \(b^2-4ac\) in your case \(a=1,b=7,c=-1\) note that \(c=-1\) not \(1\)

OpenStudy (anonymous):

no the \(-7\) part is right

OpenStudy (anonymous):

ohh

OpenStudy (anonymous):

so -2

OpenStudy (anonymous):

hold the phone you were closer before \[b^2-7ac\\ 7^2-4\times 1\times (-1)\\ 49+4\\ 53\]

OpenStudy (anonymous):

ohhhhh

OpenStudy (anonymous):

you had \(49-4=45\) but it should have been \(49+4\)

OpenStudy (anonymous):

ok i understand now

OpenStudy (anonymous):

so just change the 45 to 53 and badaboom i got an answer

OpenStudy (anonymous):

final answer is \[\frac{-7\pm\sqrt{53}}{2}\] and as you said badaboom you get the "final answer" there is nothing you can do with this , leave it

OpenStudy (anonymous):

alright awesome !

OpenStudy (anonymous):

invoice is in the mail

OpenStudy (mathstudent55):

\(x^2 + 7x = 1\) \(x^2 + 7x + \left(\dfrac{7}{2}\right)^2= 1 + \left(\dfrac{7}{2}\right)^2\) \(\left(x + \dfrac{7}{2}\right)^2= 1 + \dfrac{49}{4}\) \(\left(x + \dfrac{7}{2}\right)^2= \dfrac{4}{4} + \dfrac{49}{4}\) \(\left(x + \dfrac{7}{2}\right)^2= \dfrac{53}{4}\) \(x + \dfrac{7}{2}= \pm \sqrt{\dfrac{53}{4}}\) \(x = -\dfrac{7}{2} \pm \dfrac{\sqrt{53}}{\sqrt{4}}\) \(x = -\dfrac{7}{2} \pm \dfrac{\sqrt{53}}{2}\) \(x = -\dfrac{7 \pm \sqrt{53}}{2}\)

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