\(\frac{327\cdot412+400}{328\cdot412-12}=\frac{327\cdot412+400}{\left(327+1\right)\cdot412-12}=\)\(\frac{327\cdot412+400}{327\cdot412+1\cdot412-12}=\frac{327\cdot412+400}{327\cdot412+412-12}=\)\(\frac{327\cdot412+400}{327\cdot412+400}=\frac{1}{1}=1\)

\(\frac{327.412+400}{328.412-12}\) = \(\frac{328.412-412+400}{328.412-12}\)= \(\frac{328.412-\left[412-400\right]}{328.412-12}\) = \(\frac{328.412-12}{328.412-12}\) = 1

a)=15.2154/1505

=6462/301

b)=461179719/138076

c,=134724+400/135136-12

=135124/135124

=1

a)=15.(21/43+33?55)=15.234/215=16 14/43
b)=328.412-412+400/328.412-12=328.412-12/328.412-12=1
c)7217721 hay là 721721 vậy?
 

lấy mày tính bấm là nhanh nhất

Bằng 1 nha

học lâu giờ quên rùi

\(\frac{327.412+400}{328.412-12}=\frac{327.412+400}{\left(327+1\right).412-12}=\frac{327.412+400}{327.412+412-12}=\frac{327.412+400}{327.412+400}=1\)

\(=1+\frac{1}{3}+1+\frac{1}{15}+...+1+\frac{1}{399}.\)

\(=10+\frac{1}{1.3}+\frac{1}{3.5}+...+\frac{1}{19.21}\)

=\(10+\frac{1}{2}\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{19}-\frac{1}{21}\right)\)

=\(10+\frac{1}{2}\left(1-\frac{1}{21}\right)=10+\frac{1}{2}.\frac{20}{21}=\frac{220}{21}\)

Thanh you

\(12400:50=248\cdot50:50=248\)

\(360:15=24\cdot15:15=24\)

\(23800:25=952\cdot25:25=952\)

a ] 12 400 : 50 = 248

b ] 360 : 15 = 24

c ] 23800 : 25 = 952

mình đang cần gấp

Co h khong

Rút gọn biểu thức cho 3 ta được biểu thức mới là 

\(\frac{4}{28}+\frac{4}{70}+\frac{4}{130}+...\frac{4}{700}\)

= \(\frac{4}{4.7}+\frac{4}{7.10}+\frac{4}{10.13}+...+\frac{4}{25.28}\)

=\(\frac{4}{3}\left(\frac{3}{4.7}+\frac{3}{7.10}+\frac{3}{10.13}+...+\frac{3}{25.28}\right)\)

= \(\frac{4}{3}\left(\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+...+\frac{1}{25}-\frac{1}{28}\right)\)

= \(\frac{4}{3}\left(\frac{1}{4}-\frac{1}{28}\right)\)

= \(\frac{4}{3}.\frac{3}{14}\)

= \(\frac{2}{7}\)