Question

4.If x=3 is a solution of the equation 3x^2+ (k-1) x +9 = 0,then k =?​

Answer 1

Put the value of 3 in the equation

3×3^2+(k-1)3+9=0

27+3k-3+9=0

3k= -33

k= -11

hope this helps you.

Answer 2

f(x) = 3x^2+(k-1)x +9

f(-3) = 3×(-3)^2 +(k-1)(-3) +9

0 = 3×9+(k-1)(-3)+9

0 = 27+9+(k-1)(-3)

0 = 36-3k+3

3k = 39

k = 13