1.

What will be the value of k, if the roots of the equation (k – 4)x^2 – 2kx + (k + 5) = 0 are equal?(a) 18(b) 19(c) 20(d) 21The question was asked in unit test.Question is taken from Quadratic Equation in chapter Quadratic Equation of Mathematics – Class 10

Answer»

Correct answer is (c) 20

For explanation: Roots are EQUAL. ∴ b^2 – 4ac = 0

-(2K)^2 – 4(k – 4)(k + 5) = 0

4k^2 – 4(k^2 – 4k + 5K – 20) = 0

4k^2 – 4(k^2 + k – 20) = 0

4k^2 – 4k^2 – 4k + 80 = 0

-4k =– 80

k = \(\frac {-80}{-4}\) = 20


Discussion

No Comment Found

Related InterviewSolutions