Question

If (x – k) is a factor of f(x) = x2 – 4, what is the value of k?

Answer 1

Answer:2

Step-by-step explanation:

f[k]= k2-4

k2-4=0

k2=4

k=2

Answer 2

Step-by-step explanation:

f(x) = x² - 4

If (x - k) is a factor of x² - 4 , then x - k = 0 implies x = k

i.e. k is a zero of the quadratic polynomial x² - 4

∴ f(k) = 0 = k² - 4

k² = 4

Taking square root

∵ √x² = | x |

∴ √k² = | k | = √4 = 2

k = 2 , -2

So , k ∈ { -2 , 2 }