Question

If one of the root of $2x^2-cx+3=0$ is $3$ and another equation $2x^2-cx+d=0$ has equal roots where $c$ and $d$ are real numbers, then $d$ is

• A. $3$
• B. $49.8$
• C. $8/49$
• D. $-3$

Answer 1

Answer: (B)

$49.8$

Since, $3$ is a root of $2x^2-cx+3=0$
$\therefore$ $2{\left(3\right)}^2-c\left(3\right)+3=0$
$\Rightarrow$ $c=7$
Another equation is $2x^2-cx+d=0$
$\therefore$ $2x^2-7x+d=0$
Since the roots are equal
$\therefore B^2=4AC$
$\Rightarrow 49=4\times 2\times d\Rightarrow d=\frac{49}{8}$