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The range of a for which the equation x^...

The range of `a` for which the equation `x^2+ax-4=0` has its smaller root in the interval `(-1,2)` is

A

`(-infty, -3)`

B

(0, 3)

C

`(0, infty)`

D

` (- infty, - 3 ) cup (0, infty)`

Text Solution

Verified by Experts

The correct Answer is:
A
Clearly , `f(-1) gt 0 , f(2) lt 0 `
Now ,
` f(0) = - 4 lt 0 `
`rArr f (-1) = 1 - a - 4 gt 0 `
and ` f(2) = 4 + 2 a - 4 lt 0 `
`rArr a lt - 3 and alt 0 `
`rArr a in (-infty), - 3)`
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