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← JEE Main 2026 · 6 Apr · Shift 2
MathematicsInteger+4 / -1Question 25 of 75

JEE Main 2026 · 6 Apr · Shift 2, Mathematics question 25

Let f(x)={x3+8;x<0,x2−4;x≥0,f(x)=\begin{cases}x^3+8; & x<0,\\ x^2-4; & x\ge0,\end{cases} and g(x)={(x−8)1/3;x<0,(x+4)1/2;x≥0.g(x)=\begin{cases}(x-8)^{1/3}; & x<0,\\ (x+4)^{1/2}; & x\ge0.\end{cases} Then the number of points, where the function gofgof is discontinuous, is ________.

Answer and worked solution

Official answer: 3

Where g jumps. g(0−)=−2g(0^-)=-2 and g(0)=2g(0)=2, so g is discontinuous only at 0. So g∘fg\circ f can break where f crosses 0 or where f itself jumps.

Check each point.

  • x=0x=0: f jumps from 8 to −4, so g∘fg\circ f jumps from 12\sqrt{12} to (−12)1/3(-12)^{1/3}.
  • x=−2x=-2: f=x3+8f=x^3+8 crosses 0 from below, so g∘fg\circ f jumps from −2 to 2.
  • x=2x=2: f=x2−4f=x^2-4 crosses 0 from below, likewise.

Count: 3.

Answer: 3