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Find the Value of K for Which the Following Equations Have Real and Equal Roots: - Mathematics

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Question

Find the value of k for which the following equations have real and equal roots:

\[x^2 + k\left( 2x + k - 1 \right) + 2 = 0\]

Solution

The given equation is  \[x^2 + k\left( 2x + k - 1 \right) + 2 = 0\]

\[\Rightarrow x^2 + 2kx + k\left( k - 1 \right) + 2 = 0\]

So, a = 1, b = 2k, c = k(k − 1) + 2
We know 

\[D = b^2 - 4ac\]

\[\Rightarrow D = \left( 2k \right)^2 - 4 \times 1 \times \left[ k\left( k - 1 \right) + 2 \right]\]

\[ \Rightarrow D = 4 k^2 - 4\left[ k^2 - k + 2 \right]\]

\[ \Rightarrow D = 4 k^2 - 4 k^2 + 4k - 8\]

\[ \Rightarrow D = 4k - 8 = 4\left( k - 2 \right)\]

For equal roots, D = 0
Thus, 4(k − 2) = 0
So, k = 2.

  Is there an error in this question or solution?
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APPEARS IN

 RD Sharma Solution for Class 10 Maths (2018 (Latest))
Chapter 4: Quadratic Equations
Ex. 4.6 | Q: 4.4 | Page no. 42
 RD Sharma Solution for Class 10 Maths (2018 (Latest))
Chapter 4: Quadratic Equations
Ex. 4.6 | Q: 4.4 | Page no. 42
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Find the Value of K for Which the Following Equations Have Real and Equal Roots: Concept: Solutions of Quadratic Equations by Factorization.
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