\(P=\frac{\left(\frac{10203}{125}:\frac{24}{5}-\frac{901}{200}\right)^2+125\cdot\frac{3}{4}}{\left\{\left[\left(\frac{11}{25}\right)^2+\frac{353}{100}\right]^2-\left(\frac{11}{4}\right)^2\right\}:\frac{13}{25}}\)

\(P=\frac{\left(\frac{10203}{125}\cdot\frac{5}{24}-\frac{901}{100}\right)^2+\frac{375}{4}}{\left[\left(\frac{121}{625}+\frac{353}{100}\right)^2-\frac{121}{16}\right]\cdot\frac{25}{13}}\)

\(P=\frac{\left(\frac{3401}{200}-\frac{1802}{200}\right)^2+\frac{18750}{200}}{\left[\left(\frac{484}{2500}+\frac{8825}{2500}\right)^2-\frac{121}{16}\right]\cdot\frac{25}{13}}\)

\(P=\frac{\frac{1599}{200}^2+\frac{18750}{200}}{\left(\frac{9309}{2500}^2-\frac{121}{16}\right)\cdot\frac{25}{13}}\)

\(P=\frac{\frac{2556801}{40000}+\frac{3750000}{40000}}{\left(\frac{86657481}{6250000}-\frac{47265625}{6250000}\right)\cdot\frac{25}{13}}\)

\(P=\frac{\frac{6306801}{40000}}{\frac{39391856}{6250000}\cdot\frac{25}{13}}\)

\(P=\frac{\frac{6306801}{40000}}{\frac{2461991}{203125}}\)

đổi 2h48phut=168phut;4h40phut=280phut

gọi v(vận tốc)cả 2 xe là a,b(a,b thuộc N*)

ta có 

a/168=b/280=a+b/168+280=28/448=0.0625

suy ra:

a/168=0.0625=a=0.0625*168=10.5 km

b/280=0.0625=b=0.0625*280=17.5 km

vậy xe lửa 1 chạy với v =10.5km

      xe lửa 2 chạy với v = 17.5km

cảm ơn bn nhé!!

1/1x2+1/2x3+1/3x4+...+1/99x100+1/100x101

=1/1-1/2+1/2-1/3+1/3-1/4+...+1/99-1/100+1/100-1/101

=1/1-1/101

=100/101