Question bank/JEE Main/Mathematics

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$( - \infty, - 3) \cup (0,\infty)$

Show answer and solution▾

[IMAGE] Clearly $f( - 1) > 0,f(2) < 0$
Now $f(0) = - 4 < 0$
$\Rightarrow f( - 1) = 1 - a - 4 > 0$
And $f(2) = 4 + 2a - 4 < 0$
$\Rightarrow a < - 3anda < 0$
$\Rightarrow a \in ( - \infty, - 3)$

Source: Grass-G / M-16 Mathematics Paper 25 Nov First.docx