Mathematics
If the roots of the quadratic equation 2x2 + 8x + k = 0 are equal, then the value of k is:
2
8
4
none of these
Quadratic Equations
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Answer
Comparing 2x2 + 8x + k = 0 with ax2 + bx + c = 0 we get,
a = 2, b = 8 and c = k.
We know that,
Since equations has equal roots,
⇒ Discriminant = 0
⇒ b2 - 4ac = 0
⇒ (8)2 - 4(2)(k) = 0
⇒ 64 - 8k = 0
⇒ 8k = 64
⇒ k =
⇒ k = 8.
Hence, option 2 is the correct option.
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