When it says the "x - 1 " is the factor of that function means when you find the root of the phrase x - 1 which is x = 1 , put it in the function then you have to get zero for the answer :
thus :
[tex]f(1) = 0[/tex]
Thus :
[tex]2 \times {1}^{3} + k(1) - 9 = 0[/tex]
So :
[tex]2 + k - 9 = 0[/tex]
[tex]k - 7 = 0[/tex]
Add both sides 7
[tex]k - 7 + 7 = 0 + 7[/tex]
[tex]k = 7[/tex]
There you go...
Have a great day ❤
