Good Problem on Limits

If α, β are the roots of the equation x2 + bx + c = 0 then find

lim (1 - cos(x2 + bx + c))/(β - x)2
x->β

2 Answers

106
Asish Mahapatra ·

x2+bx+c = (x-α)(x-β)

=> lim(x→β) 2sin2[(x-α)(x-β)/2]/(x-β)2
= lim(x→β)2(x-α)2/4

= (β-α)2/2

62
Lokesh Verma ·

(α-β)2/2

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