Question

If (x + 5) is a factor of p(x) = x3 - 20x + 5k then k = ? Sk k a) 5 b) -3 c) 3 d) -5​

Answer 1

=> x + 5 = 0

=> x = -5

P(x) = x³ - 20x + 5k

=> x³ - 20x + 5k = 0

=> (-5)³ - 20 × (-5) + 5k = 0

=> -125 + 100 + 5k = 0

=> 5k = 25

=> k = 25/5 = 5