A  =       \(\dfrac{1}{3}\) + \(\dfrac{1}{3^2}\) + \(\dfrac{1}{3^3}\)+...+ \(\dfrac{1}{3^{99}}\) + \(\dfrac{1}{3^{100}}\)

   3A  = 1 + \(\dfrac{1}{3}\) + \(\dfrac{1}{3^2}\) + \(\dfrac{1}{3^3}\)+...+ \(\dfrac{1}{3^{99}}\)

3A - A = 1 - \(\dfrac{1}{3^{100}}\)

  2A     =  1 - \(\dfrac{1}{3^{100}}\)

     A     = \(\dfrac{1}{2}\) - \(\dfrac{1}{2.3^{100}}\) < \(\dfrac{1}{2}\) 

132*145+100-145*133+15

=145(132-133)+115

=-145+115=-30<0

=>132*145+100<145*133-15

\(\frac{132×145+100}{145×133-45}=1\)

= 17611 nhà bn nhớ k nha

3/2+7/6+13/12+21/20+...+133/132
=1+ 1/2 + 1+ 1/6 + 1+ 1/12 + 1+ 1/20+......+ 1+ 1/132
=(1+ 1 + 1+.....+ 1) + ( 1/2+ 1/6+1/12+ 1/20+....+ 1/132)
= 11+ ( 1/1×2+ 1/2×3+1/3×4+1/4×5+.....+1/11×12)
=11+ ( 1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+......+1/11-1/12)
=11+(1-1/12)
= 11+11/12
=143/12

3/2+7/6+13/12+21/20+...+133/132 =1+ 1/2 + 1+ 1/6 + 1+ 1/12 + 1+ 1/20+......+ 1+ 1/132 =(1+ 1 + 1+.....+ 1) + ( 1/2+ 1/6+1/12+ 1/20+....+ 1/132) = 11+ ( 1/1×2+ 1/2×3+1/3×4+1/4×5+.....+1/11×12) =11+ ( 1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+......+1/11-1/12) =11+(1-1/12) = 11+11/12 =143/12

a,132 x 1450 +100

=191400 + 100

=191500

b,145 x 133 - 45

=19285 - 45

=19240

a= 191500

b= 19240

a = 191400+100

= 191500

b = 19285 - 45

=19240