Tính giá trị của biểu thức: H= 38/50+9/20-11/30+13/42-15/56+17/72-...+197/9702-199/9900

Ta có:

920=94.5=5+44.5=54.5+44.5=14+15

1130=115.6=6+55.6=65.6+55.6=15+16

1342=136.7=7+66.7=76.7+66.7=16+17

…

1979702=19798.99=99+9898.99=9998.99+9898.99=198+199

1999900=19999.100=100+9999.100=10099.100+9999.100=199+1100

Do đó H=3850+920−1130+1342−1556+1772−...+1979702−1999900

=3850+14+15−15+16+16+17−17+18++18+19−...+198+199−199+1100=3850+14+15−15−16+16+17−17−18+18+19=3850+14+15−15+−16+16+17−17+−18+18+19−19+...+−198+198+199−199−1100=3850+14+0+0+0+0+0+...+0+0−1100=3850+14−1100=76100+25100−1100=76+25−1100=100100

= 1.

Vậy H = 1.