Given:

f(x) is continuous at x = 4 & f(4) = a + b

For f(x) to be continuous at x = 4, f(4)^– ₌ f(4) ^{+ =} f(4)

LHL = f(4)^– =

a – 1

LHL = f(4) ⁺ =

1

Since ,f(x) is continuous at x = 4 & f(4) = a + b

f(4)^–=f(4) ⁺ =f(4)

a – 1 = a + b = 1

a – 1 = 1

a = 2

a + b = 1

2 + b = 1

b = 1–2

b = –1