Tính : S= 3/ 1.4 + 3/ 4.7+ 3/ 7.10+ 3/ 10.13+ 3/ 13.16
Giải thích
S=31.4+34.7+37.10+310.13+313.16
=4−11.4+7−44.7+10−37.10+13−1010.13+16−1313.16
=41.4−11.4+74.7−44.7+107.10−37.10+1310.13−1010.13+1613.16−1313.16
=1−14+14−17+17−110+110−113+113−116
=1−116
=1516