If α and β are zeros of the quadratic polynomial x2-6x+a, find the value of a if 3α +2β =20
Answers
Step-by-step explanation:
Polynomial P(x) = x² - 6 x + a
Given α and β are the roots. To find a , if 3 α + 2 β = 20. ---(1)
From the quadratic expression:
α + β = 6 ---(2)
and α β = a --- (3)
Multiply equation (2) by 2 and subtract from (1) to get:
α = 20 -12 = 8
Substitute this value in(2) to get:
β = 6-8 = -2
Substitute these in (3) to get: a = α β = -16.
Step-by-step explanation:
x² - 6x + a
a = 1 b = -6 c = a
α +β = -b/a = 6
αβ = c/a = a
3α + 2β = 20
3α = 20 - 2β
α = (20 - 2β) / 3
α + β = 6
(20 - 2β)/3 + β = 6
multiplying by 3 on both sides
20 - 2β + 3β = 18
20 + β = 18
β = 18 - 20
β = -2
α = (20 -2β)/3
α = (20 - 2 × -2)/3
α = (20 + 4)/3
α = 8
αβ = a
8 × -2 = a
a = -16
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