Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
bài 1.tính bằng cách hợp lí nhất :
a) 1/7 + 2/7 + 3/7 + ..... 3 5/7 + 3 6/7
b) 3/5x 3 5/9 + 6/5 x 11/9
Bài 1:
a) \(2\frac{1}{4}+1\frac{1}{2}-1\frac{4}{5}\)
=\(\frac{9}{4}\)+\(\frac{3}{2}\)-\(\frac{9}{5}\)
=\(\frac{45}{20}+\frac{30}{20}-\frac{36}{20}\)
=\(\frac{39}{20}\)
b) \(2\frac{2}{3}\times3\frac{1}{4}:2\frac{3}{4}\)
\(\frac{8}{3}\times\frac{13}{4}:\frac{11}{4}\)
=\(\frac{8}{3}\times\frac{13}{4}\times\frac{4}{11}\)
=\(\frac{104}{33}\)
Bài 2:
a) \(\frac{7}{9}+\frac{4}{5}+\frac{11}{9}+\frac{6}{5}\)
=\(\left(\frac{7}{9}+\frac{11}{9}\right)+\left(\frac{4}{5}+\frac{6}{5}\right)\)
=2+2
=4
b) \(\frac{21}{36}\times\frac{39}{14}\times\frac{54}{13}\)
=\(\frac{21\times39\times54}{36\times14\times13}\)
=\(\frac{675}{100}\)
\(3\frac{25}{125}=3\frac{1}{5}=\frac{9}{5}\) \(4\frac{20}{100}=4\frac{1}{5}=\frac{21}{5}\)
\(2\frac{5}{7}=2\frac{5}{7}=\frac{19}{7}\) \(7\frac{6}{9}=7\frac{6}{9}=\frac{70}{9}\)
Giải:
\(3\frac{25}{125}=3\frac{1}{5}\)
\(2\frac{5}{7}=2\frac{10}{14}\)
\(4\frac{20}{100}=4\frac{1}{5}\)
\(7\frac{6}{9}=7\frac{12}{18}\)
học tốt!!!
\(9\frac{1}{4}+6\frac{2}{7}+7\frac{3}{5}+8\frac{2}{3}+\frac{2}{5}+\frac{1}{3}+\frac{5}{7}+\frac{3}{4}\)
\(=\left(9\frac{1}{4}+\frac{3}{4}\right)+\left(6\frac{2}{7}+\frac{5}{7}\right)+\left(7\frac{3}{5}+\frac{2}{5}\right)+\left(8\frac{2}{3}+\frac{1}{3}\right)\)
\(=\left(\frac{37}{4}+\frac{3}{4}\right)+\left(\frac{44}{7}+\frac{5}{7}\right)+\left(\frac{38}{5}+\frac{2}{5}\right)+\left(\frac{26}{3}+\frac{1}{3}\right)\)
\(=\frac{40}{4}+\frac{49}{7}+\frac{40}{5}+\frac{40}{5}+\frac{27}{3}\)
\(=10+7+8+8+9\)
\(=42\)
**** nha Bùi Xuân Lê
a) \(\frac{7}{8}\) - \(\frac{1}{3}\) = \(\frac{21}{24}\) - \(\frac{8}{24}\) = \(\frac{13}{24}\)
\(\frac{8}{9}\) + \(\frac{2}{5}\) = \(\frac{40}{45}\) + \(\frac{18}{45}\) = \(\frac{58}{45}\)
\(\frac{3}{10}\) x \(\frac{1}{6}\) = \(\frac{3\times1}{10\times6}\) = \(\frac{3}{60}\) = \(\frac{1}{20}\)
\(\frac{8}{9}\) : \(\frac{3}{7}\) = \(\frac{8}{9}\) x \(\frac{7}{3}\) = \(\frac{56}{27}\)
b) Đổi hỗn số ra phân số rồi làm tương tự câu a)
a) = 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35
b) = 1/3 x 4/5 + 1/3 x6/5 + 1/3 x 2 = 1/3(4/5 + 6/5 + 2) = 1/3 x 4 = = 4/3
c) 4/7 x 2/9 + 4/7 x 7/9 + 2/3 = 4/7 x (2/9 + 7/9) + 2/3 = 4/7 x 1 + 2/3 = 26/21
A) 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35
B) 1/3 x 4/5 + 1/3 x 6/5 + 1/3 x 2 = 1/3 x(4/5 + 6/5 x 2 ) = 1/3 x 4 = 4/3
c) TƯƠNG TỰ CÂU A VÀ B
* HOKTOT*
NHA