Let a and b be the distinct roots of a x 2 + b x + c = 0 , then lim x → α 1 - cos a x 2 + b x + c x - α 2 is equal to (a) 0 (b) a 2 α - β 2 2 (c) α - β 2 2 (d) - a 2 α - β 2 2 Share with your friends Share 0 Aarushi Mishra answered this Dear studentThe question should beLet α and β be distinct roots of the equation ax2+bx+c=0, then limx→α 1-cos ax2+bx+cx-α2If x=α and x=β are roots of ax2+bx+c=0 then by factor thoerem x-α and x-β are factors of ax2+bx+c, therefore ax2+bx+c= ax-α x-β, we have mutlipled by a so that coefficient of x2 on R.H.S. becomes equa to that on L.H.S. limx→α 1-cos ax2+bx+cx-α2=limx→α 2sin2ax2+bx+c2x-α2, since 1-cos2x=2sin2x=limx→α 2sin2ax-α x-β2x-α2=2limx→α sin ax-α x-β2x-α2=2limx→α a2x-β222a2x-β222×sin ax-α x-β2x-α2=2limx→αa2x-β222 sin ax-α x-β2ax-βx-α22=2 ×limx→αa2x-β222 limx→α sin ax-α x-β2ax-βx-α22=2×a2α-β222 limx→αsin ax-α x-β2ax-βx-α22Using limθ→0 sin θθ=1=a2α-β22 0 View Full Answer