Question

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)`

Answer 1

Correct Answer - 1
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)`