Question

5²/1*6 + 5²/6*11 + 5²/11*16 + 5²/16*21 + 5²/21*26 + 5²/26*31

Answer 1

5²/1*6 + 5²/6*11 + 5²/11*16 + 5²/16*21 + 5²/21*26 + 5²/26*31

=5(1-1/6+1/6-1/11+1/11-...+1/26-1/31)

=5(1-1/31)

=5.30/31

=150/31

Answer 2

5²/1 x 6 + 5²/6 x 11 + 5²/11 x 16 + 5²/16 x 21 + 5²/21 x 26 + 5²/26 x 31

= 5.(5/1.6 + 5/6.11 + 5/11.16 + 5/16.21 + 5/21.26 + 5/26.31)

= 5.(1 - 1/6 + 1/6 - 1/11 + 1/11 - 1/16 + 1/16 - 1/21 + 1/21 - 1/26 + 1/26 - 1/31)

= 5.(1 - 1/31)

= 5.30/31

= 150/31