Rút gọn phân số rồi tính như thường :)

\(-\frac{9991}{9992}+\frac{1}{99}-\frac{2}{19984}-\frac{5}{495}\)

\(=-\frac{9991}{9992}+\frac{1}{99}-\frac{1}{9992}-\frac{1}{99}\)

\(=\left(-\frac{9991}{9992}-\frac{1}{9992}\right)+\left(\frac{1}{99}-\frac{1}{99}\right)\)

\(=-1+0\)

\(=-1\)

\(\frac{-1}{-16}-\frac{1}{15}\)

\(=\frac{1}{16}-\frac{1}{15}\)

\(=\frac{15-16}{16\times15}\)

\(=\frac{-1}{240}\)

c. ơn bn nha

\(\frac{-1}{-16}\)-\(\frac{1}{15}\)

=\(\frac{1}{16}\)-\(\frac{1}{15}\)

=\(\frac{15}{240}\)-\(\frac{16}{240}\)

=\(\frac{15-16}{240}\)

=\(\frac{-1}{240}\)

\(-\frac{1}{16}-\frac{1}{15}\)

\(=-\left(\frac{1}{16}+\frac{1}{15}\right)\)

\(=-\frac{16+15}{16\times15}\)

\(=-\frac{31}{240}\)

31/240

đó bạn

\(-\frac{1}{16}-\frac{1}{15}=\frac{-15}{240}-\frac{16}{240}=\frac{-15-16}{240}=\frac{-31}{240}\)

25-[50-(2^3.17-2^3.14)]

=25-[50-(8.17-8.14)]

=25-[50-(136-112)]

=25-[50-24]

=25-26

=-1

|-128|: [45^2-(2010-2008.1^2010)]

=128:[45^2-(2010-2008.1)]

=128:[45^2-(2010-2008)]

=128:[45^2-2]

=128:[2025-2]

=128:2023

=0,063 (chắc mik làm sai b đấy :(  )

25-[50-(2^3.17-2^3.14)]=25-{50-[2^3.(17-14)]}

                                     =25-{50-[8.3]}

                                     =25-{50-24}

\(=\left[\frac{2xy}{\left(x-y\right).\left(x+y\right)}+\frac{x-y}{2.\left(x+y\right)}\right]:\frac{x+y}{2x}+\frac{x}{y-x}\)

\(=\frac{4xy+\left(x-y\right).\left(x-y\right)}{2.\left(x-y\right).\left(x+y\right)}.\frac{2x}{x+y}+\frac{x}{y-x}\)

\(=\frac{x^2+2xy+y^2}{\left(x-y\right).\left(x+y\right)^2}.x+\frac{x}{y-x}\)

\(=\frac{x.\left(x+y\right)^2}{\left(x-y\right).\left(x+y\right)^2}+\frac{x}{y-x}\)

\(=\frac{x}{x-y}-\frac{x}{x-y}=0\)

Bạn giùm mik nhé, tks bạn nhiều (:

sai rồi

bn nên chọn ác quỷ hay thiên thần mk chọn ÁC QUỶ

\(15.3+7.3-8.3\)

\(=3\left(15+7-8\right)\)

\(=3.14=42\)

\(16.79:77+3.32\)

\(=1264:77+96\)

\(=\frac{6192}{77}\)

15 x 3 + 7 x 3 - 8 x 3

= (15 + 7 - 8) x 3

= (22 - 8) x 3

= 14 x 3

= 42

16 x 79 : 77 + 3 x 32

= 1264 : 80 x 32

= 1264 : 2560

= 49375/100000

= 0,49375

17 x 100 - [30 - (7 - 5) x 2]

= 1700 - (30 - 2 x 2)

= 1700 - (30 - 4)

= 1700 - 26

= 1674

18 x 1 + 4 + 7 + 10 + 13 + 16 + 19 +...+ 97 + 100

= 18 x (100 + 1)

= 18 x 101

= 1818

Câu cuối mik làm đại thôi

Học tốt!!!

2378 nhé

2378,tk mk,mk tk lại

= 2378 ( vì nhân trước )

k mk đi rồi mk sẽ k lại cho mỗi người 3 cái !

Đừng quên kb nhé ! Học tốt !

số cần tìm là:\(\frac{5}{1}+\frac{2}{1}=7\)

Ds:7

Số cần tìm là:

\(\frac{5}{1}+\frac{2}{1}\) = \(\frac{7}{1}\)

Đáp số: \(\frac{7}{1}\)

\(\frac{5}{1}+\frac{2}{1}=\frac{7}{1}=7\)

M=20/112+20/280+20/520+20/832

M=20/8.14+20/14.20+20/26.20+20/26.32

M=20/6.(6/8.14+6/14.20+6/20.26+6/26.32)

M=20/6.(1/8-1/14+1/14-1/20+1/20-1/26+1/26-1/32)

M=20/6.(1/8-1/32)

M=20/6.3/32

M=5/16

\(M=\frac{20}{112}+\frac{20}{280}+\frac{20}{520}+\frac{20}{832}\)

\(M=\frac{20}{8.14}+\frac{20}{14.20}+\frac{20}{20.26}+\frac{20}{26.32}\)

\(M=\frac{20}{6}\left(\frac{6}{8.14}+\frac{6}{14.20}+\frac{6}{20.26}+\frac{6}{26.32}\right)\)

\(M=\frac{10}{3}.\left(\frac{1}{8}-\frac{1}{14}+\frac{1}{14}-\frac{1}{20}+\frac{1}{20}-\frac{1}{26}+\frac{1}{26}-\frac{1}{32}\right)\)

\(M=\frac{10}{3}.\left(\frac{1}{8}-\frac{1}{32}\right)\)

\(M=\frac{10}{3}.\left(\frac{4}{32}-\frac{1}{32}\right)\)

\(M=\frac{10}{3}.\frac{3}{32}\)

\(M=\frac{5}{16}\)

Chúc bạn học tốt !!!!