Let f : R → R be a function defined as . Then f is
For x = 1
R.H.L = a + b
L.H.L = 5
So to be continuous at x = 1
a + b = 5 …………(i)
for x = 3
R.H.L. = b + 15
L.H.L = a + 3b
b + 15 = a + 3b
a + 2b = 15 ………….(ii)
for x = 5
R.H.L = 30
L.H.L = b + 25
b + 25 = 30
b = 5.
From equation (ii)
a = 10
but a = 10 and b = 5 does not satisfied equation (i)
So f (x) is discontinuous for a R and b R
Let's analyze the continuity of the piecewise function f(x) defined as:
A function is continuous at a point if the left-hand limit, right-hand limit, and the function's value at that point all exist and are equal. For a piecewise function, we must check the points where the definition changes: x = 1, x = 3, and x = 5.
Left-hand limit (x→1⁻): f(x) = 5 ⇒ limit = 5
Right-hand limit (x→1⁺): f(x) = a + bx ⇒ limit = a + b(1) = a + b
Function value at x=1: f(1) = 5
For continuity: a + b = 5 ...(Equation 1)
Left-hand limit (x→3⁻): f(x) = a + bx ⇒ limit = a + b(3) = a + 3b
Right-hand limit (x→3⁺): f(x) = b + 5x ⇒ limit = b + 5(3) = b + 15
Function value at x=3: f(3) = b + 5(3) = b + 15
For continuity: a + 3b = b + 15 ⇒ a + 2b = 15 ...(Equation 2)
Left-hand limit (x→5⁻): f(x) = b + 5x ⇒ limit = b + 5(5) = b + 25
Right-hand limit (x→5⁺): f(x) = 30 ⇒ limit = 30
Function value at x=5: f(5) = 30
For continuity: b + 25 = 30 ⇒ b = 5 ...(Equation 3)
From Equation 3: b = 5
Substitute b = 5 into Equation 1: a + 5 = 5 ⇒ a = 0
Substitute b = 5 into Equation 2: a + 2(5) = 15 ⇒ a + 10 = 15 ⇒ a = 5
We get a contradiction: a must be both 0 (from Eq1) and 5 (from Eq2). Therefore, no values of a and b can satisfy all three continuity conditions simultaneously.
The function is not continuous for any values of a and b.
Continuity of Functions: A function f(x) is continuous at a point x = c if: All three values must exist and be equal.
Piecewise Functions: Functions defined by different expressions over different intervals. Special attention must be paid to the points where the definition changes to check for continuity.
The fundamental condition for continuity at a point x = c: