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Question
Find the value of ‘k’ for which the quadratic equation 2kx2 – 40x + 25 = 0 has real and equal roots.
Solution
Given quadratic equation is 2kx2 – 40x + 25 = 0
On comparing the above equation with ax2 + bx + c = 0, we get
a = 2k, b = –40, c = 25
For real and equal roots, D = 0
i.e., b2 – 4ac = 0
or, (–40)2 – 4(2k)(25) = 0
⇒ 1600 – 200k = 0
⇒ 200k = 1600
⇒ k = 8
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