(x+4)((x^2) - kx - 5) is expanded and simplified. The coefficient of the x^2 term twice the coefficient of the x term. Work out the value of k.

(x + 4) (x² - kx - 5) = x³ - kx² - 5x + 4x² - 4kx - 20 = x³ + (4-k)x² + (-5-4k)x - 20.The coefficients are: (4-k) of x² and (-5-4k) of x. Now we can write the equation:(4-k) = 2(-5 - 4k) /expand4 - k = -10 - 8k /+8k4 + 7k = -10 /-47k = -14 /divide by 7k = -2