Let
f(x) = ax + 3 if x > 2
f(x) = x + 5 if -2 <= x <= 2
f(x) = 2x - b if x <= -2
Find a+b if the piecewise function is continuous
Let:
f1(x) = ax + 3
f2(x) = x + 5
f3(x) = 2x - b
If the function is continuous, that means f1(2) must equal f2(2) and also that f3(-2) must equal f2(-2)
f1(2) = f2(2)
a(2) + 3 = 2 + 5
2a + 3 = 7
2a = 4
a = 2
f3(-2) = f2(-2)
2(-2) - b = -2 + 5
-4 - b = 3
-b = 7
b = -7
And so
a + b = 2 + -7 = -5