Question

x^2 + 4x+k = 0 has real roots . find k

Answer 1

Answer:

x² + 4x + k = 0

(1) for real and equal roots, b² - 4ac = 0

=> 4² - 4*1*k = 0

=> 16 - 4k = 0

=> 4k = 16

=> k = 4

(2) for real and unequal roots, b² - 4ac > 0

=> 4² - 4*1*k > 0

=> 16 - 4k > 0

=> 16 > 4k

=> 4k < 16

=> k < 4