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Question
The equation `3x^2 – 12x + (n – 5) = 0` has equal roots. Find the value of n.
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Solution
`3"x"^2 – 12"x" + (n – 5) = 0`
Here a = 3, b = − 12 and c = n – 5
Given: equation has equal roots
Then D = 0
⟹ `"b"^2 – 4"ac" = 0`
⟹ `[− 12]^2 – 4(3)("n" – 5) = 0`
⟹ 144 – 12n + 60 = 0
⟹ − 12n = − 204
⟹ `"n"=(-204)/-12=17`
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