Observation formula: 1 = 1 square, 1 + 3 = 4 = 2 square, 1 + 3 + 5 = 9 = 3 square This law is expressed by algebraic expression (n is a positive integer) 1 + 3 + 5 + 7 + 9 + +(2n-1)=( ) emergency
This is an arithmetic sequence
=Square of n
This is an arithmetic sequence
=Square of n