Question

If x = -7/2 is zero of 2x² + Kx -12 then find k.​

Answer 1

Answer:

$x = \frac{ - 7}{2} \\ \\ 2 {x}^{2} + kx - 12 = 0 \\ 2 { (\frac{ - 7}{2}) }^{2} + k( \frac{ - 7}{2} ) - 12 = 0 \\ (2 \times \frac{49}{4} ) - \frac{7k}{2} - 12 = 0 \\ \frac{49}{2} - \frac{7k}{2} - 12 = 0 \\ \frac{49 - 7k - 24}{2} = 0 \\ \frac{ - 7k + 25}{2} = 0 \\ \frac{ - 7k}{2} + \frac{25}{2} = 0 \\ \frac{ 25}{2} = \frac{7k}{2} \\ 25 \times2 = 7k \times 2 \\ 50 = 14k \\ \frac{50}{14} = k \\ \large{ \boxed{ \underline{ \underline{ \bf{ \frac{25}{7}}}} = k}}$