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Mathematics 15 Online
OpenStudy (anonymous):

I don't understand question 3c in the following post

OpenStudy (anonymous):

OpenStudy (stamp):

What is the equation in question?

OpenStudy (anonymous):

the one in part b

hartnn (hartnn):

so, you got till t+1/t=4 right ? now multiply both sides by 't' , what u get ?

OpenStudy (anonymous):

t^2 + 1 = 4t

hartnn (hartnn):

so, can u solve the quadratic equation t^2-4t+1=0 ??

OpenStudy (anonymous):

(t-2)^2 - 3

hartnn (hartnn):

(t-2)^2 = 3 take square root on both sides.

hartnn (hartnn):

actually u get \(t - 2 =\pm \sqrt{(3)}\)

OpenStudy (anonymous):

yes my mistake

hartnn (hartnn):

which completes part c

hartnn (hartnn):

have douts on part d also ?

hartnn (hartnn):

*doubts

OpenStudy (anonymous):

i thought i had to sub in t from the previous answer

OpenStudy (anonymous):

and i didnt understand how to solve for x

hartnn (hartnn):

yes. \(t =2\pm \sqrt{(3)} \\ (\sqrt{2+\sqrt3})^x=2\pm \sqrt{(3)}\)

OpenStudy (anonymous):

so x = 2

hartnn (hartnn):

\( (\sqrt{2+\sqrt3})^x=2\pm \sqrt{(3)} \\ (\sqrt{2+\sqrt3})^x=2+ \sqrt{(3)} \\ and \\ (\sqrt{2+\sqrt3})^x=2- \sqrt{(3)}\)

hartnn (hartnn):

for \( (\sqrt{2+\sqrt3})^x=2+ \sqrt{(3)}\) you get x=2, correct

hartnn (hartnn):

what about \( (\sqrt{2+\sqrt3})^x=2- \sqrt{(3)}\) ?

OpenStudy (anonymous):

2-sqrt3 = 1/(2+sqrt3) is that right

hartnn (hartnn):

yes, use that.

hartnn (hartnn):

2-sqrt3 = 1/(2+sqrt3) = (2+sqrt3)^(-1)

OpenStudy (anonymous):

x = -3

hartnn (hartnn):

-3 ?? O.o

hartnn (hartnn):

how ?

OpenStudy (anonymous):

wait its -2

hartnn (hartnn):

\(\checkmark\) good :)

OpenStudy (anonymous):

thanks for your help, you're a lifesaver ;D

hartnn (hartnn):

welcome ^_^

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