Question

If the determinant of $3x^2-4x+k=0$ is $64$ the $k=$_________________

• A. $-4$
• B. $4$
• C. $-8$
• D. $8$

Answer 1

The correct option is B $4$

Given,

The determinant of $3x^2-4x+k=0$ is $64$

The determinant of a quadratic equation $a{x}^2+bx+c=0$ is given by

$determinant=b^2-4ac$

Hence, from given quadratic equation we have

$a=3;b=-4;c=k;\text{and determinant =64}$

$(-4{)}^2-4\times 3\times k=64$

$16-12k=64$

$12k=16-64$

$k=-\frac{48}{12}$

$k=-4$