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Continuity and Differentiability · Question 10

JEE Main 2026 (Online) 24th January Evening ShiftMCQMedium📈 Topic in 35% papers+4−1
1

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)

JEE Main 2026 (Online) 24th January Evening Shift

Keep practising — Continuity and Differentiability

2

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
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3

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  1. 1
  2. 2
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4

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
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5

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7

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8

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  1. 64
  2. 48
  3. 36
  4. 72
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9

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 .

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