the sum of the first n positive perfect squares , where n is a positive integer , is given by the formula n 3 / 3 + cn 2 + n / 6 , where c is a constant . what is the sum of the first 15 positive perfect squares ?
"for n = 1 , 1 = 1 / 3 + c + 1 / 6 1 = 1 / 2 + c = > c = 1 / 2 15 * 15 * 15 / 3 + 1 / 2 * 15 * 15 + 15 / 6 = 1240 answer : c"
divide(divide(multiply(multiply(15, add(15, const_1)), add(multiply(15, 2), const_1)), 6), divide(multiply(multiply(15, add(15, const_1)), add(multiply(15, 2), const_1)), 6))