Q44 / 90 · KVPY 2019 (SB/SX) · Mathematics

Let A1, A2 and A3 be the regions on R2 defined by

A1=x,y:x≥0,y≥0,2x+2y-x2-y2>1>x+y

A2=x,y:x≥0,y≥0,x+y>1>x2+y2

A3=x,y:x≥0,y≥0,x+y>1>x3+y3

Denote by A1, A2 and A3 the areas of the regions A1, A2 and A3 respectively. Then

  • A
    A1>A2>A3
  • B
    A1>A3>A2
  • Correct answer
    C
    A1=A2<A3
  • D
    A1=A3>A2

Solution

Area of region defined by 

A1=(x,y):x≥0,y≥0,2x+2y-x2-y2>1>x+y is A1.

Figure

Similarly, A2 is the area of region defined by 

A2=x,y:x≥0,y≥0,x+y>1>x2+y2

Here, A1=A2

Figure

and area A3 is the area of region defined by A3=x,y:x≥0,y≥0,x+y>1>x3+y3
then A3>A2=A1

Figure

Hence, the correct answer is option: 'C'.

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