Question

The values of k for which the roots are real and equal of the following equation
$4x^2$ + kx + 9 = 0

is $k=\pm 12$

• A. True
• B. False

Answer 1

The correct option is A True

$4x^2+kx+9=0$

$\Rightarrow$ Here, $a=4,b=k,c=9$

$\Rightarrow$ It is given that roots are real and equal.

$\therefore$ $b^2-4ac=0$

$\Rightarrow$ $(k{)}^2-4(4\left)\right(9)=0$

$\Rightarrow$ $k^2-144=0$

$\Rightarrow$ $k^2=144$

$\therefore$ $k=\pm 12$

$\therefore$ We can see value of $k$ given in question is correct.