Verified Solution • 2025–26 Session moderate

QJEEM21Ma8a35: JEE Main 2021 Mathematics - Class 11 JEEM21Ma8a35 Solution: If the functions are defined as and , then what is the common…

If the functions are defined as f(x)=xf(x) = \sqrt x and g(x)=1−xg(x) = \sqrt {1 - x} , then what is the common domain of the following functions :

f + g, f −- g, f/g, g/f, g −- f where (f±g)(x)=f(x)±g(x),(f/g)x=f(x)g(x)(f \pm g)(x) = f(x) \pm g(x),(f/g)x = {{f(x)} \over {g(x)}}

Multiple Choice Options

  • A 0≤x≤10 \le x \le 1
  • B 0≤x<10 \le x < 1
  • C 0<x<10 < x < 1
  • D 0<x≤10 < x \le 1

Step-by-Step Verified Solution

f+g=x+1−xf + g = \sqrt x + \sqrt {1 - x}

⇒x≥0\Rightarrow x \ge 0 & 1−x≥0⇒x∈[0,1]1 - x \ge 0 \Rightarrow x \in [0,1]

f−g=x−1−xf - g = \sqrt x - \sqrt {1 - x}

⇒x≥0\Rightarrow x \ge 0 & 1−x≥0⇒x∈[0,1]1 - x \ge 0 \Rightarrow x \in [0,1]

f/g=x1−xf/g = {{\sqrt x } \over {\sqrt {1 - x} }}

⇒x≥0\Rightarrow x \ge 0 & 1 - x &gt; 0 \Rightarrow x \in [0,1)

g/f=1−xxg/f = {{\sqrt {1 - x} } \over {\sqrt x }}

⇒1−x≥0\Rightarrow 1 - x \ge 0 & x &gt; 0 \Rightarrow x \in (0,1]

g−f=1−x−xg - f = \sqrt {1 - x} - \sqrt x

⇒1−x≥0\Rightarrow 1 - x \ge 0 & x≥0⇒x∈[0,1]x \ge 0 \Rightarrow x \in [0,1]

⇒\Rightarrow x∈(0,1)x \in (0,1)

Related Learning Resources & Exam Preparation