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NCERT]12. At t minutes past 2 pm the time needed by the minutes hand and a clock to show3 pm was found to be 3 minutes less thanminutes. Find t. |
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Answer» Given time needed by the minutes hand show (t^2/4) – 3Hence the quadratic equation becomes, (t^2/4) – 3 = 60 – t(t^2– 12)/4 = 60 – t(t^2– 12) = 240 – 4 tt^2– 12 – 240 + 4 t = 0t^2+ 4t – 252 = 0t^2+ 18t – 14t – 252 = 0t(t + 18) – 14(t + 18) = 0(t + 18)(t – 14) = 0(t + 18) = 0 or (t – 14) = 0∴t = - 18 or t = 14Since t cannot be negative, t = 14 |
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