6. In the our lecture notes a closed form for $2 was found using the closed form for $1. Use a similar strategy to find a closed for $3 using the closed form for S, and $2. In other words find a closed form for S3 = 13 + 23 + 3 3 + . + 13 using the expansion: (x+ 1)* = x4+4x3 + 6x2+4x+1 by plugging in x = 1, x = 2, x = 3, ., x = n. Simplify your answer as much as possible your fully simplified form should show that $3 is a perfect square. Note: a perfect square is an integer that is the square of an integer, for example 4, 9, 625 are perfect squares since they equal 22, 32, 252