How to obtain root of this quadratic equation

Question

I got this quadratic equation in a problem $T^2 - 2T - 40 = 0$, but i am unable to find the roots of this equation. Is any other concept hidden in this equation? Please help.

I am basically a Bipc [biology physics and chemistry] student of India and do not have a good mathematical base.

have you tried the quadratic formula? – Jam Jul 12 '14 at 09:06 — Jam, Jul 12 '14 at 09:06
http://en.wikipedia.org/wiki/Completing_the_square – lab bhattacharjee Jul 12 '14 at 09:08 — lab bhattacharjee, Jul 12 '14 at 09:08

score 1 · Accepted Answer · answered Jul 12 '14 at 09:11

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If you do not know the solution of quadratic equations and want to solve $$x^2-2x-40=0$$ start completing the square writing $$x^2-2x-40=x^2-2x+1-40-1=(x-1)^2-41=0$$ So, $$x-1=\pm\sqrt{41}$$ and so $$x=1\pm\sqrt{41}$$

Is this clear in that form ?

answered Jul 12 '14 at 09:11

Claude Leibovici

260,315

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You are very welcome ! Cheers :) – Claude Leibovici Jul 12 '14 at 09:20

How to obtain root of this quadratic equation

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