\(\dfrac{8}{7}\) của 56 là....................
Kết quả của phép nhân \(\dfrac{49}{56}\)X\(\dfrac{64}{35}\) là:
A. 7/5 B. 8/5 C. 56/5 D.8/7
gấp ạ
Tìm \(x\):
\(\dfrac{x}{7}-\dfrac{7}{8}=\dfrac{-25}{56}\)
Ta có: \(\dfrac{x}{7}-\dfrac{7}{8}=\dfrac{-25}{56}\)
\(\Leftrightarrow\dfrac{x}{7}=\dfrac{-25}{56}+\dfrac{7}{8}=\dfrac{-25+49}{56}=\dfrac{3}{7}\)
hay x=3
Vậy: x=3
\(\dfrac{x}{7}-\dfrac{7}{8}=-\dfrac{25}{56}\)
\(\Rightarrow\dfrac{x}{7}-\dfrac{49}{56}=-\dfrac{25}{56}\)
\(\Rightarrow\dfrac{x}{7}=-\dfrac{25}{56}+\dfrac{49}{56}=\dfrac{3}{7}\)
\(\Rightarrow x=3\)
\(\dfrac{x}{7}-\dfrac{7}{8}=\dfrac{-25}{56}\\ \Rightarrow\dfrac{x}{7}=\dfrac{-25}{56}+\dfrac{7}{8}\\ \Rightarrow\dfrac{x}{7}=\dfrac{24}{56}=\dfrac{3}{7}\\ \Rightarrow x=3\)
Vậy x = 3
Viết 8\(\dfrac{5}{7}\) dưới dạng phân số là:
a.\(\dfrac{56}{7}\) b.\(\dfrac{61}{7}\) c.\(\dfrac{72}{7}\) d.\(\dfrac{81}{7}\)
VIẾT 8\(\dfrac{5}{7}\) DƯỚI DẠNG PHÂN SỐ LÀ:
A.\(\dfrac{56}{7}\) B.\(\dfrac{61}{7}\) C.\(\dfrac{72}{7}\) D.\(\dfrac{81}{7}\)
Tìm x, biết :
a) \(\left(\dfrac{31}{20}-\dfrac{26}{45}\right).\dfrac{-36}{35}< x< \left(\dfrac{51}{56}+\dfrac{8}{21}+\dfrac{1}{3}\right).\dfrac{8}{13}\)
b) \(\dfrac{-3}{5}.x=\dfrac{1}{4}+0,75\)
c) \(\left(\dfrac{1}{7}-\dfrac{1}{3}\right).x=\dfrac{28}{3}.\left(\dfrac{1}{4}-\dfrac{1}{7}\right)\)
d) \(\dfrac{5}{7}.x=\dfrac{9}{8}-0,125\)
e)\(\left(\dfrac{2}{11}+\dfrac{1}{3}\right).x=\left(\dfrac{1}{7}-\dfrac{1}{8}\right).56\)
Mấy bài này bạn tự làm đi, chuyển vế tìm x gần giống cấp I mà.
b)\(\dfrac{-3}{5}.x=\dfrac{1}{4}+0,75\)
=>\(\dfrac{-3}{5}.x=1\)
=>\(x=1:\dfrac{-3}{5}\)
=>\(x=\dfrac{-5}{3}\)
Vậy \(x=\dfrac{-5}{3}\)
Bài 1
a) Tính
3\(\dfrac{5}{7}\) - 2\(\dfrac{5}{7}\) +6\(\dfrac{3}{8}\)
B) đặt tính rồi tính
23,04 + 5,182 56 + 38,29
C) tính nhanh
\(\dfrac{12x4x72}{36x2x9}\)
c: \(\dfrac{12\cdot4\cdot72}{36\cdot2\cdot9}=\dfrac{1}{3}\cdot2\cdot8=\dfrac{16}{3}\)
Bài 1
a) Tính
3\(\dfrac{5}{7}\) - 2\(\dfrac{5}{7}\) + 6\(\dfrac{3}{8}\)
B) đặt tính rồi tính
23,04 + 5,182 56 + 38,29
C) tính nhanh
\(\dfrac{12x4x72}{36x2x9}\)
c: \(\dfrac{12\cdot4\cdot72}{36\cdot2\cdot9}=\dfrac{1}{3}\cdot2\cdot8=\dfrac{16}{3}\)
1.Tính nhanh:
e)\(\dfrac{\dfrac{1}{6}-\dfrac{1}{39}+\dfrac{1}{51}}{\dfrac{1}{8}-\dfrac{1}{12}+\dfrac{1}{68}}\)
f)\(\dfrac{7}{8}+\dfrac{7}{56}+\dfrac{7}{154}+...+\dfrac{7}{1400}\)
e) \(\dfrac{\dfrac{1}{6}-\dfrac{1}{39}+\dfrac{1}{51}}{\dfrac{1}{8}-\dfrac{1}{12}+\dfrac{1}{68}}=\dfrac{\dfrac{1}{3}\left(\dfrac{1}{2}-\dfrac{1}{13}+\dfrac{1}{17}\right)}{\dfrac{1}{4}\left(\dfrac{1}{2}-\dfrac{1}{13}+\dfrac{1}{17}\right)}=\dfrac{1}{3}:\dfrac{1}{4}=\dfrac{3}{4}\)
bài 3 thực hiện phép tính
a\(\dfrac{5}{8}+\dfrac{3}{17}+\dfrac{4}{18}+\dfrac{20}{-17}+\dfrac{-2}{9}+\dfrac{21}{56}\)
b\(\left(\dfrac{9}{16}+\dfrac{8}{-27}\right)+\left(1+\dfrac{7}{16}+\dfrac{-19}{27}\right)\)
c\(\left(\dfrac{13}{5}+\dfrac{7}{16}\right)+\left(\dfrac{-15}{16}+\dfrac{6}{15}\right)\) d \(\left(6-2\dfrac{4}{5}\right).3\dfrac{1}{8}-1\dfrac{3}{5}:\dfrac{1}{4}\)
a) Ta có: \(\dfrac{5}{8}+\dfrac{3}{17}+\dfrac{4}{18}+\dfrac{20}{-17}+\dfrac{-2}{9}+\dfrac{21}{56}\)
\(=\left(\dfrac{3}{17}-\dfrac{20}{17}\right)+\left(\dfrac{2}{9}-\dfrac{2}{9}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)\)
\(=-1+1=0\)
b) Ta có: \(\left(\dfrac{9}{16}+\dfrac{8}{-27}\right)+\left(1+\dfrac{7}{16}+\dfrac{-19}{27}\right)\)
\(=\left(\dfrac{9}{16}+\dfrac{7}{16}\right)+\left(\dfrac{-8}{27}-\dfrac{19}{27}\right)+1\)
=1-1+1=1