find the value of "k" given that one solution of the equation 2x^2-kx+12=0 is -3/2

Question

Need help finding the answer, it's a complicated question and I can't find it ANYWHERE

Answer 1

It seems to me that all you need to do is to substitute -3/2 in for x--then you have an equation in which the only unknown is k!

Answer 2

2x² - kx + 12 = -3/2

2x² - kx + 12 + 3/2 = 0         add 3/2 to both sides

2x² - kx + 13 1/2 = 0             combine

4x² - 2kx + 27 = 0                 multiply both sides by 2

 

(2x² - 3)(2x² - 9) = 4x² -24x + 27

 

-2k = -24

k = 12