Question

[Miuna Yuri]

Bài 1: Tính 

a) -7/9 . 2/3/4    (2/3/4 là hỗn số : 2 là số nguyên, 3/4 là phân số)

b) 2/3 + 1/3 . (-2/5)

c) 3/4 . 15/1/3 - 3/4 . 43/1/3

d) (-49,1) . 13/27 - 58,9 . 13/27

e) 0,375 : (-4,5)

f) 3/1/7 : (-1/3/7)

g) 9/1/3 : 4/2/3 - 2

h) (7/3/4 : 0,3125 + 4,5 . 2/2/45) : (-8,5)

Bài 2: Tính giá trị biểu thức

A = (-6/11) . 7/10 . (11/-6).(-20)

B = (-1/9) . (-17/29) . 58/51

C = (-3/7) . 5/11 + (-5/14) . 5/11

D = (1/1/27 . 12/23 . 9/14) : (-3/23)

Bài 3: Tìm x

a) 3/7 . x - 2/5 . x = -17/35

b) (3/4 . x -9/16) . [1/3 + (-3/5) : x] = 0

c) (x + 3/5) . (x + 1) = 0

Answer 1

[Huy hoàng indonaca]

1.

a) \(\frac{-7}{9}.2\frac{3}{4}=\frac{-7}{9}.\frac{11}{4}=\frac{-77}{36}\)

b) \(\frac{2}{3}+\frac{1}{3}.\frac{-2}{5}=\frac{2}{3}+\frac{-2}{15}=\frac{8}{15}\)

c) \(\frac{3}{4}.15\frac{1}{3}-\frac{3}{4}.43\frac{1}{3}=\frac{3}{4}.\frac{46}{3}-\frac{3}{4}.\frac{130}{3}=\frac{23}{2}-\frac{65}{2}=-21\)

d) \(\left(-49,1\right).\frac{13}{27}-58,9.\frac{13}{27}=\frac{13}{27}.\left(-49,1-58,9\right)=\frac{13}{27}.\left(-108\right)=-52\)

e) \(0,375:\left(-4,5\right)=\frac{-1}{12}\)

f) \(3\frac{1}{7}:\left(-1\frac{3}{7}\right)=\frac{22}{7}:\frac{-10}{7}=\frac{-11}{5}\)

g) \(9\frac{1}{3}:4\frac{2}{3}-2=\frac{28}{3}:\frac{14}{3}-2=2-2=0\)

h) \(\left(7\frac{3}{4}:0,3125+4,5.2\frac{2}{45}\right):\left(-8,5\right)=\left(\frac{31}{4}:\frac{5}{16}+\frac{9}{2}.\frac{92}{45}\right):\frac{-17}{2}=\left(\frac{124}{5}+\frac{46}{5}\right):\frac{-17}{2}=34:\frac{-17}{2}=-4\)

Answer 2

[I have a crazy idea]

Bài 1 : Tính:

a)

\(\frac{-7}{9}.2\frac{3}{4}=\frac{-7}{9}.\frac{11}{4}=\frac{-77}{36}\)

b) 

\(\frac{2}{3}+\frac{1}{3}.\frac{-2}{5}=\frac{2}{3}+\frac{-2}{15}=\frac{10}{15}+\frac{-2}{15}=\frac{8}{15}\)

c)

\(\frac{3}{4}.15\frac{1}{3}-\frac{3}{4}.43\frac{1}{3}=\frac{3}{4}.\frac{46}{3}-\frac{3}{4}.\frac{130}{3}\)\(=\frac{23}{2}-\frac{65}{2}=\frac{-42}{2}=-21\)

....

Tự lm tiếp dạng như v

Bài 2 : 

\(A=\frac{-6}{11}.\frac{7}{10}.\frac{11}{-6}.-20=\left(\frac{-6}{11}.\frac{11}{-6}\right).\left(\frac{7}{10}.-20\right)\)\(=1.\left(-14\right)=-14\)

.....

Bài 3 : 

\(\frac{3}{7}.x-\frac{2}{5}.x=\frac{-17}{35}\)

\(\Leftrightarrow\frac{3}{7}-\frac{2}{5}.x=\frac{-17}{35}\)

\(\Leftrightarrow\frac{1}{35}x=\frac{-17}{35}\)

\(\Leftrightarrow x=\frac{-17}{35}:\frac{1}{35}\)

\(\Leftrightarrow x=\frac{-17}{35}.35=-17\)