Find the value of p for which the quadratic equation

x2 – 2px + 1 = 0 has no real roots.

The given quadratic equation is x2 – 2px + 1 = 0.


And, Discriminant D of the quadratic equation ax2 + bx + c = 0 is given by –


D = b2 – 4ac


Comparing the equation ax2 + bx + c = 0 with given quadratic equation is x2 – 2px + 1 = 0, we get –


a = 1, b = – 2p and, c = 1


D = (– 2p)2 – 4(1)(1) = 4p2 – 4 = 4(p2 – 1)


For no real roots,


D < 0


4(p2 – 1) < 0


p2 – 1 < 0


(p + 1)(p – 1) < 0


p (– 1,1)


Thus, p can take any values between – 1 and 1 for no real roots of given quadratic equation.


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