Q31 / 90 · NTA Abhyas (JEE Main) 2020 · Mathematics · Limits

The value of limx→∞⁡2x1/2+3x1/3+4x1/4+.....+x1/n2x-31/2+2x-31/3+....+2x-31/n is

  • Correct answer
    A
    2
  • B
    2
  • C
    13
  • D
    0

Solution

Given, 

limx→∞⁡2x1/2+3x1/3+....+nx1/n2x-31/2+2x-31/3+...+2x-31/n

=limh→0⁡21h1/2+31h1/3+....+n1h1/n1h1/22-3h1/2+1h1/32-3h1/3+.....+1h1/n2-3h1/n

On putting x=1h as x→∞ , h→ 0

=limh→0⁡2+3h12 - 13+4h12 - 14+....+nh12 - 1n2-3h1/2+h12 - 132-3h1/3+....+h12 - 1n2-3h1/n

=2+0+0+0+.......21/2+0+0+.......=2.

 

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

More Limits Questions