Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
a) $2 \times \frac{3}{{14}} = \frac{2}{1} \times \frac{3}{{14}} = \frac{{2 \times 3}}{{1 \times 14}} = \frac{6}{{14}} = \frac{3}{7}$
b) $3 \times \frac{4}{9} = \frac{3}{1} \times \frac{4}{9} = \frac{{3 \times 4}}{{1 \times 9}} = \frac{{12}}{9} = \frac{4}{3}$
c) $\frac{7}{{18}} \times 6 = \frac{7}{{18}} \times \frac{6}{1} = \frac{{7 \times 6}}{{18 \times 1}} = \frac{{42}}{{18}} = \frac{7}{3}$
d) $\frac{{19}}{{12}} \times 0 = \frac{{19}}{{12}} \times \frac{0}{1} = \frac{{19 \times 0}}{{12 \times 1}} = 0$
1, \(\frac{7}{12}=\frac{1}{12}+\frac{2}{12}+\frac{4}{12}=\frac{1}{12}+\frac{1}{6}+\frac{1}{3}\)
2, \(S=\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+...+\frac{1}{19x20}\)
\(=\left(\frac{1}{2}-\frac{1}{3}\right)+\left(\frac{1}{3}-\frac{1}{4}\right)+\left(\frac{1}{4}-\frac{1}{5}\right)+...+\left(\frac{1}{19}-\frac{1}{20}\right)\)
\(=\frac{1}{2}-\frac{1}{20}=\frac{9}{20}\)
Chúc bạn học tốt.
Tổng mới hai phân số đó là :
\(\frac{5}{19}+\frac{1}{19}+\frac{2}{19}=\frac{8}{19}\)
ĐS : . . .
tổng mới là:
5/19 + 1/19 + 2/19 = 8/19
đáp số: 8/19
k nha
\(a.\) \(\frac{4}{15}.\frac{7}{9}+\frac{4}{15}.\frac{2}{9}\)
\(=\frac{4}{15}\left(\frac{7}{9}+\frac{2}{9}\right)\)
\(=\frac{4}{15}.\frac{9}{9}\)
\(=\frac{4}{15}.1\)
\(=\frac{4}{15}\)
\(b.\) \(\frac{13}{19}.\frac{23}{11}-\frac{13}{19}.\frac{8}{11}-\frac{13}{19}.\frac{4}{11}\)
\(=\frac{13}{19}\left(\frac{23}{11}-\frac{8}{11}-\frac{4}{11}\right)\)
\(=\frac{13}{19}.\frac{11}{11}\)
\(=\frac{13}{19}.1\)
\(=\frac{13}{19}\)
a)4/15 x(7/9+2/9)=4/15x1=4/15
b)13/19x(23/11-8/11-4/11)13/19x1=13/19
a) \(\frac{4}{7}=\frac{16}{28}\)
\(\frac{9}{12}=\frac{3}{4}=\frac{21}{28}\)
b) \(\frac{13}{12}=\frac{39}{36}\)
\(\frac{19}{18}=\frac{38}{36}\)
c) \(\frac{1}{5}=\frac{2}{10}\)
d) \(\frac{1}{3}=\frac{21}{63}\)
\(\frac{2}{7}=\frac{18}{63}\)
\(\frac{4}{9}=\frac{28}{63}\)
a/ 4/7 = 1-3/7 và 9/12 = 1-3/12
vì 3/7>3/12 nên 1-3/7<1-3/12
Vậy 4/7<9/12
b/ 13/12 = 1+1/12 và 19/18 = 1+1/18
Vì 1/12>1/18 nên 13/12>19/18
a, \(\frac{5}{11}\times\frac{7}{25}+\frac{15}{11}\times\frac{1}{5}\)
\(=\frac{5}{11}\times\frac{7}{25}+\frac{5}{11}\times\frac{3}{5}\)
\(=\frac{5}{11}\times\left(\frac{7}{25}+\frac{3}{5}\right)\)
\(=\frac{5}{11}\times\frac{22}{25}\)
\(=\frac{2}{5}\)
b, \(\frac{3}{7}\times\frac{25}{19}-\frac{1}{7}\times\frac{18}{19}\)
\(=\frac{1}{7}\times\frac{75}{19}-\frac{1}{7}\times\frac{18}{19}\)
\(=\frac{1}{7}\times\left(\frac{75}{19}-\frac{18}{19}\right)\)
\(=\frac{1}{7}\times3\)
\(=\frac{3}{7}\)
TL
Đáp án là B nhé
_HT_
@@@@@
B bạn nhé