22 + 62 + 102 + 142 - 12 - 52 - 92 - 132 का मूल्य क्या है?

अभिव्यक्ति,

= (2² – 1²) + (6² – 5²) + (10² – 9²) + (14² – 13²)

= (2 × 1 + 1) + (2 × 5 + 1) + (2 × 9 + 1) + (2 × 13 + 1)

[ (n + 1)² – n2 = n2 + 2n + 1 – n2 = 2n + 1]

= 3 + 11 + 19 + 27 = 60