JAMIA 2021 — Mathematics PYQ
JAMIA | Mathematics | 2021Find the number of points, where is non differentiable at

Find the number of points, where f(x)=∣2x+1∣−3∣x+2∣+∣x2+x−2∣ is non differentiable at
2
(Correct Answer)3
4
0
2
The function is given by:
We find the zeros for each absolute value term:
2x+1=0⟹x=−1/2
x+2=0⟹x=−2
x2+x−2=0⟹(x+2)(x−1)=0⟹x=−2,1
The potential points of non-differentiability are x=−2,−1/2,1.
A function ∣g(x)∣ is non-differentiable at x=a if g(a)=0 and g′(a)=0. If multiple absolute value terms share a root, they might cancel each other out.
At x=−1/2:
Only ∣2x+1∣ is zero. The other terms are smooth and non-zero.
Result: Non-differentiable.
At x=1:
Only ∣x2+x−2∣ is zero. Since g(x)=x2+x−2 has a simple root at x=1 (g′(1)=3=0), the slope will jump.
Result: Non-differentiable.
At x=−2:
Both −3∣x+2∣ and ∣x2+x−2∣ are zero. Let's check the behavior near x=−2:
For x near −2, ∣2x+1∣ is negative inside, so ∣2x+1∣=−(2x+1)=−2x−1.
Near x=−2, (x−1) is approximately −3.
The terms −3∣x+2∣ and 3∣x+2∣ cancel each other out on both sides of x=−2.
Left Hand Derivative (LHD):
Right Hand Derivative (RHD):
Since LHD=RHD=−2, the function is differentiable at x=−2.
The points of non-differentiability are:
Number of points: 2
The function is given by:
We find the zeros for each absolute value term:
2x+1=0⟹x=−1/2
x+2=0⟹x=−2
x2+x−2=0⟹(x+2)(x−1)=0⟹x=−2,1
The potential points of non-differentiability are x=−2,−1/2,1.
A function ∣g(x)∣ is non-differentiable at x=a if g(a)=0 and g′(a)=0. If multiple absolute value terms share a root, they might cancel each other out.
At x=−1/2:
Only ∣2x+1∣ is zero. The other terms are smooth and non-zero.
Result: Non-differentiable.
At x=1:
Only ∣x2+x−2∣ is zero. Since g(x)=x2+x−2 has a simple root at x=1 (g′(1)=3=0), the slope will jump.
Result: Non-differentiable.
At x=−2:
Both −3∣x+2∣ and ∣x2+x−2∣ are zero. Let's check the behavior near x=−2:
For x near −2, ∣2x+1∣ is negative inside, so ∣2x+1∣=−(2x+1)=−2x−1.
Near x=−2, (x−1) is approximately −3.
The terms −3∣x+2∣ and 3∣x+2∣ cancel each other out on both sides of x=−2.
Left Hand Derivative (LHD):
Right Hand Derivative (RHD):
Since LHD=RHD=−2, the function is differentiable at x=−2.
The points of non-differentiability are:
Number of points: 2
