1.tính nhanh
A= 1/2+1/210+1/240+1/276+1/306+1/342
tính nhanh
A= 1 phần 182+1 phần 210 + 1 phần 240 + 1 phần 276 + 1 phần 306 + 1 phần 342
Tính Nhanh
\(A=\frac{1}{182}+\frac{1}{210}+\frac{1}{240}+\frac{1}{276}+\frac{1}{306}+\frac{1}{342}\)
A=1/13.14+1/14.15+1/15.16+1/16.17=1/17.18+1/18.19
A=1/13-1/14+1/14-1/15+1/15-1/16+1/16-1/17+1/18-1/19
A=1/13-1/19
A=6/247
Tính hợp lý nhất
a, 1/210+1/240+1/272+1/306
b, 191/210+161/240+129/272+95/306
giúp mình với huhuhu
a, 1/210+1/240+1/272+1/306
= 1/14.15 + 1/15.16 + 1/16.17 +1/17.18
= 1/14 - 1/15 + 1/15 - 1/16 +1/16 - 1/17 + 1/17 - 1/18
= 1/14 - 1/18 = 1/63
a) \(\frac{1}{210}+\frac{1}{240}+\frac{1}{272}+\frac{1}{306}\)
=\(\frac{1}{14.15}+\frac{1}{15.16}+\frac{1}{16.17}+\frac{1}{17.18}\)
=\(\frac{1}{14}-\frac{1}{15}+\frac{1}{15}-\frac{1}{16}+\frac{1}{16}-\frac{1}{17}+\frac{1}{17}-\frac{1}{18}\)
=\(\frac{1}{14}-\frac{1}{18}=\frac{1}{63}\)
b)\(\frac{191}{210}+\frac{161}{240}+\frac{129}{272}+\frac{95}{306}\)
=\(\frac{191}{14.15}+\frac{161}{15.16}+\frac{129}{16.17}+\frac{95}{17.18}\)
=\(\frac{191}{14}-\frac{191}{15}+\frac{161}{15}-\frac{161}{16}+\frac{129}{16}-\frac{129}{17}+\frac{95}{17}-\frac{95}{18}\)
tự làm tiếp
1/210+1/240+1/272+1/306
1/210+1/240+1/272+1/306
=1/112+1/272+1/306
=3/238+1/306
=1/63
1/210+1/240+1/272+1/306
\(\frac{49}{5360}\)+\(\frac{1}{272}\)+\(\frac{1}{306}\)=\(\frac{73}{5695}\)+\(\frac{1}{306}\)=\(\frac{97}{6030}\)
1/210+1/240+1/272+1/306
\( {1 \over 210}+{1 \over 240}+{1 \over 272}+{1 \over 306}\)
Tính nhanh : A = 364-(364/210+334/240+302/272+268/306+232/342+194/380)
1 phần 210 + 1phần 240 + 1 phần 272 + 1 phần 306