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Question
If a and b are roots of the equation x2 + ax + b = 0, then a + b =
Options
1
2
-2
-1
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Solution
The given quadric equation is `x^2 + ax + b = 0`, and their roots are a and b
Then find the value of (a + b)
Let `alpha and beta` be two roots of given equation
And, a = 1, b = a and , c = b
Then, as we know that sum of the roots
`alpha + beta = (-b)/a`
`a + b = (-a)/1`
` = -a`
And the product of the roots
`alpha . beta = c/a`
`a xx b = b /1`
` a = 1`
Putting the value of a in above
Therefore, the value of `a+ b = -1`.
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