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Continuity and Differentiability

JEE Main 2026 (Online) 24th January Evening ShiftMCQMedium📈 Topic in 32% papers+4−1
Ques. 1JEE Main 2026, 24 January (Evening Shift)

Let [t] denote the greatest integer less than or equal to t. If the function f(x) = cases b2 ( 2 [ 2( x + x) x ] ), & x < 0 \ x - 12 2xx3, & x > 0 \ a, & x = 0 cases is continuous at x = 0, then a2 + b2 is equal to :

  1. 12
  2. 58
  3. 34
  4. 916

Answer

(3) 34

Solution

Right-hand limit:

x 0+ x - x xx3

= x 0+ xx 1 - xx2 = 1 12 = 12 ⇒ RHL = 12

Left-hand limit: ( x + x) x = 2 x + x x = 1 - 2 x + 12 2x

For small x < 0, 2x < 0, so this value is slightly less than 1.

⇒ 2( x + x) x is slightly less than 2 1.57 (and greater than 1)

⇒ [ 2( x + x) x ] = 1

⇒ LHL = b2 2 = b2

Continuity at x = 0: b2 = a = 12

∴ a2 + b2 = 14 + 12 = 34

Answer: (3)

Keep practising — Continuity and Differentiability

Ques. 2JEE Main 2026, 23 January (Morning Shift)

Let f(x) = cases ax2 + 2ax + 34x2 + 4x - 3 & , x - 32, 12 \ b & , x = - 32, 12 cases be continuous at x = - 32. If f f(x) = 75, then x is equal to:

  1. 1.4
  2. 2
  3. 1
  4. 0
Ques. 3JEE Main 2026, 23 January (Evening Shift)

If f(x) = cases a|x| + x2 - 2( |x|)( |x|)x & , x 0 \ b & , x = 0 cases is continuous at x = 0, then a + b is equal to :

  1. 1
  2. 2
  3. 0
  4. 4
Ques. 4JEE Main 2026, 22 January (Evening Shift)

Let [ ] denote the greatest integer function, and let f(x) = \ 2x, x2 \. Let S = \x (-2, 2) : the function g(x) = |x| [x2 ] is discontinuous at x\. Then x S f(x) equals

  1. 2 - 2
  2. 2 6 - 3 2
  3. 1 - 2
  4. 6 - 2 2
Ques. 5JEE Main 2025, 7 April (Morning Shift)

The number of points of discontinuity of the function f(x) = [ x22 ] - [ x], x [0, 4], where [ ] denotes the greatest integer function, is .

Ques. 6JEE Main 2025, 7 April (Evening Shift)

If the function f(x) = ( x) - ( x) x - x is continuous at x = 0, then f(0) is equal to .

Ques. 7JEE Main 2025, 4 April (Morning Shift)

Let m and n be the number of points at which the function f(x) = \x, x3, x5, , x21 \, x R, is not differentiable and not continuous, respectively. Then m + n is equal to .

Ques. 8JEE Main 2025, 3 April (Morning Shift)

Let f(x) = cases (1 + ax)1/x, & x < 0 \ 1 + b, & x = 0 \ (x+4)1/2 - 2(x+c)1/3 - 2, & x > 0 cases be continuous at x = 0. Then ea bc is equal to:

  1. 64
  2. 48
  3. 36
  4. 72
Ques. 9JEE Main 2025, 29 January (Evening Shift)

Let the function f(x)= (x2-1 ) |x2-ax+2 |+ |x| be not differentiable at the two points x= =2 and x= . Then the distance of the point ( , ) from the line 12x+5y+10=0 is equal to :

  1. 5
  2. 2
  3. 4
  4. 3
Ques. 10JEE Main 2025, 28 January (Morning Shift)

Let f(x) = cases 3x, & x < 0 \ \1 + x + [x], x + 2[x]\, & 0 x 2 \ 5, & x > 2 cases where [.] denotes greatest integer function. If and are the number of points, where f is not continuous and is not differentiable, respectively, then + equals .

Ques. 11JEE Main 2025, 24 January (Evening Shift)

Let [x] denote the greatest integer function, and let m and n respectively be the numbers of the points, where the function f(x)=[x]+|x-2|, -2<x<3, is not continuous and not differentiable. Then m+n is equal to :

  1. 6
  2. 9
  3. 8
  4. 7

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