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Grade Upto college levelDifferential Calculus

If α is a repeated root of ax2 + bx + c = 0, then Limx→α tan(ax2 + bx + c) / (x - α)2 is ???

Profile image of Mainak Chakraborty
16 Years agoGrade Upto college level
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Profile image of Badiuddin askIITians.ismu Expert
16 Years ago

Dear Mainak

α is a repeated root of ax2 + bx + c = 0

so   ax2 + bx + c=a(x-α)2

now  Limx→α tan(ax2 + bx + c) / (x - α)

         =Limx→α [tana(x-α)2 ]/ (x - α)2

        =Limx→α a[tana(x-α)2 ]/ a(x - α)2

        =a             because   Limx→0 tanx /x   = 1 

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