Question

For what positive value of $m$, the equation ${12x}^2+4(m+1)x+3=0$ will have equal roots?

• A. $1$
• B. $4$
• C. $3$
• D. $2$

Answer 1

Answer: (D)

$2$

Given equation is:

${12x}^2+4(m+1)x+3=0$
For equal roots, we have
$D=0$

$\Rightarrow b^2-4ac=0$
$\{4(m+1){\}}^2-4\left(12\right)\left(3\right)=0$
${16(m+1)}^2-144=0$
$\Rightarrow (m+1{)}^2=9$
$m+1=3$
$\therefore m=2$