a/b nhân 4 cộng 1/6 = 17/6 số phải tìm là bao nhiêu

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Mỗi bài mình làm một dạng thôi nhé!

1) \(\left(\frac{3}{2}-\frac{x}{y}\right)+\frac{5}{7}=\frac{11}{14}\)

\(\Rightarrow\frac{x}{y}=\frac{3}{2}-\left(\frac{11}{14}-\frac{5}{7}\right)=\frac{10}{7}\)

2) a) 

\(\frac{17}{9}+\frac{19}{13}+\frac{14}{6}+\frac{7}{13}+\frac{10}{6}+\frac{1}{9}\)

\(=\left(\frac{17}{9}+\frac{1}{9}\right)+\left(\frac{19}{13}+\frac{7}{13}\right)+\left(\frac{14}{6}+\frac{10}{6}\right)\)

\(=2+2+4\)

\(=8\)

3) a) 

\(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{42}\)

\(A=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{6.7}\)

\(A=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{6}-\frac{1}{7}\)

\(A=\frac{1}{1}-\frac{1}{7}=\frac{6}{7}\)

4) a)

\(y.\frac{5}{6}=1+\frac{1}{2}\)

\(\Rightarrow y.\frac{5}{6}=\frac{3}{2}\)

\(\Rightarrow y=\frac{3}{2}.\frac{6}{5}=\frac{9}{5}\)

a) y = 5/14 : 6/7

y = 5/12 

vậy y = 5/12

b) y = 4/9 x 2/3 

y = 8/27 

vậy t = 8/27

c) y = 1/2 - 3/10 

y = 1/5

vậy y = 1/5

d) y = 5/6 - 1/3

y = 1/2

vậy y = 1/2

a) y : 4/11 x 3/5 = 27/4

y : 4/11 = 27/4 : 3/5

y : 4/11 = 45/4

y = 45/4 x 4/11

y = 45/11

b) y + 7/2 - 5/9 = 14/3

y + 7/2 = 14/3 + 5/9

y + 7/2 = 47/9

y = 47/9 - 7/2

y = 31/18

a) y : 4/11 x 3/5 = 27/4

y : 4/11 = 27/4 : 3/5

y : 4/11 = 45/4

y = 45/4 x 4/11

y = 45/11
b) y + 7/2 - 5/9 = 14/3

y + 7/2 = 14/3 + 5/9

y + 7/2 = 47/9

y = 47/9 - 7/2

y = 31/18

\(\)a) \(y\) : \(\dfrac{4}{11}\) x \(\dfrac{3}{5}\) \(=\) \(\dfrac{27}{4}\)                   b) \(y\) \(+\) \(\dfrac{7}{2}\) \(-\) \(\dfrac{5}{9}\) \(=\) \(\dfrac{14}{3}\)

    \(y\) : \(\dfrac{4}{11}\)        \(=\) \(\dfrac{27}{4}:\dfrac{3}{5}\)                 \(y\) \(+\) \(\dfrac{7}{2}\)          \(=\) \(\dfrac{14}{3}\) \(+\) \(\dfrac{5}{9}\) 

    \(y\) : \(\dfrac{4}{11}\)        \(=\) \(\dfrac{45}{4}\)                       \(y\) \(+\) \(\dfrac{7}{2}\)           \(=\) \(\dfrac{47}{9}\)

    \(y\)                \(=\) \(\dfrac{45}{4}\) x \(\dfrac{4}{11}\)              \(y\)                    \(=\) \(\dfrac{47}{9}-\dfrac{7}{2}\)

    \(y\)                \(=\) \(\dfrac{45}{11}\)                      \(y\)                     \(=\) \(\dfrac{31}{18}\)

a) => y+42+2y= -12-14+2y

y+2y-2y = -12-14-42

y= -68

b) => 15+y-5-5y= -12-5y

y-5y+5y= -12-15+5

y = -22

c) => 2y+5-8y+21= -3-5y-2

2y-8y+5y= -3-2-5-21

-y= -31=>y=31

d)=> -13+3y+23= -120+y

3y-y= -120+13-23

2y= -130=>y= -65

e) => -21+32+5y= 16+4y

5y-4y= 16+21-32

y= 5

bài 1

a)y-(-42-2y) = (-12) - 14 +2y

y +42 + 2y = -12 -14 +2y

3y + 42 = -26 +2y

y = -68

b)15-(-y+5)-5y=-(12+5y+2)

15+y-5-5y=-12-5y-2

10-4y=-14-5y

-4y+5y=-14-10=-24

c)2y-(-5+8y-21)=-3-(5y+2)

2y+5-8y+21=-3y-5y-2

-6y+26=-8y-2

-6y+8y=-2-26

2y=-28

y=-28/2=-14

bài 1

A)37/60

B)13/45

C)1/4

bài 2

a)42/25:y/5=5/6

y=10,08

b)27/y:9/4=3/7

y=28

Mk cần gấp để nộp ạ

a) \(\left(x-2\right)\left(y-3\right)=14\\ \left(x-2\right)\left(y-3\right)=1\cdot14=14\cdot1=2\cdot7=7\cdot2=\left(-1\right)\left(-14\right)=\left(-14\right)\left(-1\right)=\left(-2\right)\left(-7\right)=\left(-7\right)\left(-2\right)\)

Ta có bảng sau:

Vậy \(\left(x;y\right)\in\left\{\left(3;17\right);\left(16;4\right);\left(4;10\right);\left(9;5\right);\left(1;-11\right);\left(-12;2\right);\left(0;-4\right);\left(-5;1\right)\right\}\)

b) \(\left(x-5\right)\left(y+5\right)=21\\ \left(x-5\right)\left(y+5\right)=1\cdot21=21\cdot1=3\cdot7=7\cdot3=\left(-1\right)\left(-21\right)=\left(-21\right)\left(-1\right)=\left(-3\right)\left(-7\right)=\left(-7\right)\left(-3\right)\)

Ta có bảng sau:

Vậy \(\left(x;y\right)\in\left\{\left(6;16\right);\left(26;-4\right);\left(8;2\right);\left(12;-2\right);\left(4;-26\right);\left(-16;-6\right);\left(2;-12\right);\left(-2;-8\right)\right\}\)

c) \(x\left(y-1\right)-6\left(y-1\right)=25\\ \left(x-6\right)\left(y-1\right)=25\\ \left(x-6\right)\left(y-1\right)=1\cdot25=25\cdot1=5\cdot5=\left(-1\right)\left(-25\right)=\left(-25\right)\left(-1\right)=\left(-5\right)\left(-5\right)\)

Ta có bảng sau:

Vậy \(\left(x;y\right)\in\left\{\left(7;26\right);\left(31;2\right);\left(11;6\right);\left(5;-24\right);\left(-19;0\right);\left(1;-4\right)\right\}\)