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Solve for n:    `n^2+n = 910` ``I can't use logarithms and stuff like that.. Thanks

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sophiaba | Student, Grade 10 | eNoter

Posted October 15, 2011 at 10:32 PM via web

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Solve for n:    `n^2+n = 910`

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I can't use logarithms and stuff like that.. Thanks

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hala718 | High School Teacher | (Level 1) Educator Emeritus

Posted October 15, 2011 at 11:37 PM (Answer #1)

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`n^2 +n= 910`

`==> n^2 +n -910 = 0`

Now we have a quadratic equation. Then, we will use the quadratic formula to find the roots.

==> Let x be a root for the quadratic functions.

==> x = `(-b+-sqrt(b^2-4ac))/(2a)`

`==> n1= (-1+sqrt(1+4*910))/2 = (-1+2sqrt910)/2= 29.666`

`==> n2 = (-1-2sqrt910)/2 = -30.666`

`==> n= { 29.666, -30.666}`

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