Tìm x biết ( 1/2 - 1/4 ) : x = 1/2 + 1/6 + 1/12 + 1/20 + ... + 1/ 132
Giải thích
12−34:x=12+16+112+120+...+1132 14:x=11×2+12×3+13×4+...+111×12 14:x=1−12+12−13+13−14+...+111−112 14:x=1−112 14:x=1112 x=14:1112 x=311
12−34:x=12+16+112+120+...+1132 14:x=11×2+12×3+13×4+...+111×12 14:x=1−12+12−13+13−14+...+111−112 14:x=1−112 14:x=1112 x=14:1112 x=311