Multiple choice

The sum of the first n terms of the series ${ 1 }^{ 2 }+2.{ 2 }^{ 2 }+{ 3 }^{ 2 }+2.{ 4 }^{ 2 }+{ 5 }^{ 2 }+2.{ 6 }^{ 2 }+...$ is $\dfrac { n{ \left( n+1 \right) }^{ 2 } }{ 2 } $ when n is even. When n is odd the sum is

  1. $\dfrac { 3n\left( n+1 \right) }{ 2 } $
  2. $\dfrac { { n }^{ 2 }\left( n+1 \right) }{ 2 } $
  3. $\dfrac { { n\left( n+1 \right) }^{ 2 } }{ 4 } $
  4. ${ \left[ \dfrac { n\left( n+1 \right) }{ 2 } \right] }^{ 2 }$
Reveal answer Fill a bubble to check yourself
A Correct answer

Keep practicing — related questions