nb + ( x1 + x 2 + ... + x n )m = ( y1 + y 2 + ... + y n ) 2 2 ( x1 + x2 + ... + xn )b + ( x12 + x 2 + ... + x n )m = ( x1 y1 + x 2 y 2 + ... + x n y n ) 1 d a b  −1  and D = ad − bc ≠ 0 , then A =  A= If c d D − c    − b . a   reff r  = 1 +  − 1  m m 1 − (1 + i ) − n  P = R  i   P = A(1 + i ) − n R= Si (1 + i ) n − 1 A = P(1 + i ) n  (1 + i ) n − 1 S = R  i   A = P(1 + rt ) R= Pi 1 − (1 + i ) − n I = Prt i= r m n = mt