Question

3y^2-ky+8,find k if the value of y is 2/3

Answer 1

$3 {y}^{2} - ky + 8 = 0 \\ 3( { \frac{2}{3} )}^{2} - k( \frac{2}{3} ) + 8 = 0 \\ 3 \times \frac{4}{9} - \frac{2k}{3} + 8 = 0 \\ \frac{4}{3} - \frac{2k}{3} + 8 = 0 \\ 4 - 2k + 24 = 0 \\ 2k = 28 \\ k = 14$