Question

Determine the value of k for which the quadratic eqation 4z2 2(k + 1) z + (k + 4) = 0 has equal roots

Answer 1

Answer:

k = -3 or 5

Step-by-step explanation:

The quadratic has equal roots

=> the discriminant is equal to zero

=> ( 2(k+1) )² - 4×4×(k+4) = 0

=> 4(k+1)² - 16(k+4) = 0

=> (k+1)² - 4(k+4) = 0

=> k² + 2k + 1 - 4k - 16 = 0

=> k² - 2k + 1 = 16

=> (k-1)² = 16

=> k-1 = ±4

=> k = 1 ± 4

=> k = -3 or 5