Q2 of 108 Page 44

Find that value of k in the following quadratic equation whose roots are real and equal:

kx2 – 5x + k = 0


When we compare the above quadratic equation with the generalized one we get,

ax2 + bx + c = 0


a = k


b = -5


c = k


Since the quadratic equations have real and equal roots,


b2 – 4ac = 0 for real and equal roots


⟹ (-5) 2 – (4 × k × k) = 0


⟹ 25 - 4k2 = 0


⟹ 4k2 = 25


⟹ k2 = 25/4


⟹ k= ± 5/2


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