Question

For f(x) = x² - 3x - 9 and g(x) = x – 7, find (f – g)(x).

Answer 1

We know that According to Algebra of Real Functions :

If f and g are two real functions which are defined under the same domain then (f - g)(x) = f(x) - g(x)

Given f(x) = x² - 3x - 9 and g(x) = x - 7

⇒ (f - g)(x) = f(x) - g(x)

⇒ (f - g)(x) = x² - 3x - 9 - (x - 7)

⇒ (f - g)(x) = x² - 3x - 9 - x + 7

⇒ (f - g)(x) = x² - 4x - 2