[5] 次の周期 2 の周期関数f(z) のフーリエ級数展開を求めよ. (0 ≤ x < π), (-π < x≤ 0). { (1) f(x) = -x+ T x + T (3) f(x) = | sinx|(-T ≤ x ≤ π) (5) f(x) = x² (-T < x <T) (2) f(x) = (4) f(x) = X x + T sin x 0 (0 < x < π), (-π < x < 0). (0<x< π), (π<x<0). (6)ƒ(x) = x(x² − x²) (-π<x<π)