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Mathematics 8 Online
OpenStudy (ytrewqmiswi):

solutions

OpenStudy (ytrewqmiswi):

\[[x^2]+[2x]=3x\] []=greatest integer function\[x \in [0,2]\] find the values of x

OpenStudy (welshfella):

by inspection one value is 0.

OpenStudy (ytrewqmiswi):

yes :)

OpenStudy (welshfella):

oh so is 1 agreed?

OpenStudy (ytrewqmiswi):

yes

OpenStudy (welshfella):

If we square both sides we get x^4 + 4x^3 + 4x^2 = 9x^2

OpenStudy (welshfella):

x^4 + 4x^3 - 5x^2 = 0 x^2(x^2 + 4x - 5) = 0 x^2(x + 5)(x - 1) = 0 x = 0, 1 , -5

OpenStudy (ytrewqmiswi):

but is it ok to square nd simplify like that when u have greatest integer function there?

OpenStudy (welshfella):

to be honest i'm not sure 1 would be greatest integer function i guess

OpenStudy (welshfella):

I'll check it out

OpenStudy (ytrewqmiswi):

ok

OpenStudy (welshfella):

[0,2] must be the domain so the greatest integer function would be 1

OpenStudy (welshfella):

-5 is an extraneous solution

OpenStudy (ytrewqmiswi):

yes

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