If sum of the zeroes of ky2+2y is equal to twice their product then k is?
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Question :
If sum of the zeroes of ky² +2y - 3k is equal to twice their product then k is?
Solution:
We have f(x) = ky² + 2y - 3k
On comparing with ax² + bx + c, we get
a = k, b = 2, c = -3k
Let α,β be the zeroes of f(x).
Sum of zeroes(α + β) = -b/2a
=> α + β = -2/k
Product of zeroes = c/a
=> αβ = -3k/k
=> αβ = -3
It is said that Sum of zeroes is equal to twice their product.
∴ α + β = 2αβ
=> -2/k = 2(-3)
=> 2/k = 6
=> 2 = 6k
=> k = 1/3
Hence, the value of k = 1/3.
#BeBrainly
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Solution:
We have f(x) = ky² + 2y - 3k
We have f(x) = ky² + 2y - 3kOn comparing with ax² + bx + c, we get
We have f(x) = ky² + 2y - 3kOn comparing with ax² + bx + c, we get a = k, b = 2, c = -3k
We have f(x) = ky² + 2y - 3kOn comparing with ax² + bx + c, we get a = k, b = 2, c = -3kLet α,β be the zeroes of f(x).
We have f(x) = ky² + 2y - 3kOn comparing with ax² + bx + c, we get a = k, b = 2, c = -3kLet α,β be the zeroes of f(x).Sum of zeroes(α + β) = -b/2a
We have f(x) = ky² + 2y - 3kOn comparing with ax² + bx + c, we get a = k, b = 2, c = -3kLet α,β be the zeroes of f(x).Sum of zeroes(α + β) = -b/2a=> α + β = -2/k
We have f(x) = ky² + 2y - 3kOn comparing with ax² + bx + c, we get a = k, b = 2, c = -3kLet α,β be the zeroes of f(x).Sum of zeroes(α + β) = -b/2a=> α + β = -2/kProduct of zeroes = c/a
We have f(x) = ky² + 2y - 3kOn comparing with ax² + bx + c, we get a = k, b = 2, c = -3kLet α,β be the zeroes of f(x).Sum of zeroes(α + β) = -b/2a=> α + β = -2/kProduct of zeroes = c/a=> αβ = -3k/k
We have f(x) = ky² + 2y - 3kOn comparing with ax² + bx + c, we get a = k, b = 2, c = -3kLet α,β be the zeroes of f(x).Sum of zeroes(α + β) = -b/2a=> α + β = -2/kProduct of zeroes = c/a=> αβ = -3k/k=> αβ = -3
∴ α + β = 2αβ
∴ α + β = 2αβ=> -2/k = 2(-3)
∴ α + β = 2αβ=> -2/k = 2(-3)=> 2/k = 6
∴ α + β = 2αβ=> -2/k = 2(-3)=> 2/k = 6=> 2 = 6k
∴ α + β = 2αβ=> -2/k = 2(-3)=> 2/k = 6=> 2 = 6k=> k = 1/3
∴ α + β = 2αβ=> -2/k = 2(-3)=> 2/k = 6=> 2 = 6k=> k = 1/3Hence, the value of k = 1/3.
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