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# If the Equation ( 1 + M 2 ) X 2 + 2 M C X + ( C 2 − a 2 ) = 0 Has Equal Roots, Prove that C2 = A2(1 + M2). - CBSE Class 10 - Mathematics

#### Question

If the equation $\left( 1 + m^2 \right) x^2 + 2 mcx + \left( c^2 - a^2 \right) = 0$ has equal roots, prove that c2 = a2(1 + m2).

#### Solution

The given equation $\left( 1 + m^2 \right) x^2 + 2 mcx + \left( c^2 - a^2 \right) = 0$, has equal roots

Then prove thatc^2 = (1 + m^2).

Here,

a = (1 + m^2), b = 2mc and, c = (c^2 -  a^2)

As we know that D = b^2 - 4ac

Putting the value of a = (1 + m^2), b = 2mc and, c = (c^2 -  a^2)

D = b^2 - 4ac

 = {2mc}^2 - 4xx (1 +m^2) xx (c^2 - a^2)

 = 4 (m^2 c^2) - 4(c^2 -a^2 + m^2c^2 - m^2 a^2)

 = 4m^2c^2 - 4c^2 + 4a^2 - 4m^2 c^2 + 4m^2a^2

 = 4a^2 + 4m^2 a^2 = 4c^2

The given equation will have real roots, if D  = 0

4a^2 + 4m^2 a^2 - 4c^2 = 0

4a^2 + 4m^2a^2 = 4c^2

4a^2 + (1 + m^2 ) = 4c^2

a^2 (1 +m^2) = c^2

Hence, c^2 = a^2 (1 + m^2).

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Solution If the Equation ( 1 + M 2 ) X 2 + 2 M C X + ( C 2 − a 2 ) = 0 Has Equal Roots, Prove that C2 = A2(1 + M2). Concept: Nature of Roots.
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