If α and βare the zeroes of a quadratic polynomial x2 + x – 2 then find the value
of 1/α - 1/β
Answers
Solution
Given :-
Let,
- Quadratic Polynomial is , p(x) = x² + x - 2 .
- α and β are the zeroes of this Equation
Find :-
- Value of (1/α - 1/β )
Explantion
Using Formula
★ Sum of zeroes = -( coefficient of x)/(coefficient of x²)
★ Product of zeroes = ( constant part)/(coefficient of x ²)
So, Now
==> Sum of zeroes = -1/1
==> α + β = -1 _______________(1)
And,
==> Product of zeroes = -2/1
==> α . β = -2________________(2)
By, equ(1)
==> α = -1 - β _____________(3)
Keep in equ(2)
==> ( -1 - β ) . β = -2
multiply by (-ve) sign in both side
==> ( 1 + β ) . β = 2
==> β² + β - 2 = 0
==> β² + 2β - β - 2 = 0
==> β(β + 2) - 1( β + 2) = 0
==> ( β + 2)(β - 1) = 0
==> (β + 2) = 0 Or, ( β - 1) = 0
==> β = -2 Or, β = 1
keep value of β in equ(3)
When,
- β = -2
==> α = -1 - (-2)
==> α = -1 + 2
==> α = 1
When,
- β = 1
==> α = -1 - 1
==> α = -2
Now, Calculate value of (1/α - 1/β)
==> (1/α - 1/β) = ( β - α )/α β
But, we know
★ Difference of roots always be positive .
So,
==> (1/α - 1/β) = | ( β - α )| /α β
Now, keep required values
where
- α = 1 , β = -2
==> (1/α - 1/β) = | ( -2 - 1)|/(1×-2)
==> (1/α - 1/β) = | ( -3)|/(-2)
We know,
- Module give always positive value
==> (1/α - 1/β) = 3/(-2)
==> (1/α - 1/β) = -3/2
Hence
- Value will be = -3/2 .
Answer:
-3/2
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