Phương trình nào biểu diễn 36 nhỏ hơn một số, y, bằng 13?

A. y - 36 = 13

B. 36 - y = 13

C. 13 - y = 36

D. 36 + y = –13

a)

 \(\frac{{28}}{9} \cdot 0,7 + \frac{{28}}{9} \cdot 0,5 = \frac{{28}}{9}.\left( {0,7 + 0,5} \right)\)

b)

\(\begin{array}{l}\frac{{36}}{{13}}:4 + \frac{{36}}{{13}}:9\\ = \frac{{36}}{{13}}.\frac{1}{4} + \frac{{36}}{{13}}.\frac{1}{9}\\ = \frac{{36}}{{13}}.\left( {\frac{1}{4} + \frac{1}{9}} \right)\\ = \frac{{36}}{{13}}.\frac{{13}}{{36}} = 1\end{array}\)

 \(\begin{array}{l}\frac{{36}}{{13}}:(4 + 9)\\ = \frac{{36}}{{13}}:13\\ = \frac{{36}}{{13}}.\frac{1}{{13}}\\ = \frac{{36}}{{169}}\end{array}\)

Suy ra \(\frac{{36}}{{13}}:4 + \frac{{36}}{{13}}:9\) \( \ne \) \(\frac{{36}}{{13}}:(4 + 9)\).

A) \(y=5X-\frac{18.2}{18}=135X-2=13x=3\)

B)\(y=\frac{5x-36}{18}=13\frac{5x}{18}-2=13\frac{5x}{18}=15\frac{x}{18}=3x=54\)

sai bet te be nhe

a, 5x-36:18=13

5x-2=13

x=5-2

x=3

b,(5x-36):18=13

5x-36=13x18

5x-36=234

5x=234+36

5x=270

x=270:5

x=54

cho mình nhé:):):):):):):)@@@@@@@#######

Đặt \(A=\frac{13}{3}+\frac{13}{6}+\frac{13}{10}+\frac{13}{15}+\frac{13}{21}+\frac{13}{28}+\frac{13}{36}+\frac{13}{45}+\frac{13}{55}\)

\(A=\frac{26}{6}+\frac{26}{12}+\frac{26}{20}+\frac{26}{30}+\frac{26}{42}+\frac{26}{56}+\frac{26}{72}+\frac{26}{90}+\frac{26}{110}\)

\(A=26\left(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}+\frac{1}{110}\right)\)

\(A=26\left(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}+\frac{1}{10.11}\right)\)

\(A=26\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{10}-\frac{1}{11}\right)\)

\(A=26\left(\frac{1}{2}-\frac{1}{11}\right)\)

\(A=26.\frac{9}{22}\)

\(A=\frac{117}{11}\)

Vậy \(A=\frac{117}{11}\)

Chúc bạn học tốt ~ 

a: =36-90=-54

b: =-13(74+1)+13*25

=-13*75+13*25

=-13*50=-650

\(36+\left(-90\right)=-54\)

\(-13.74+13.\left(5^2\right)+\left(-13\right)\)

\(=-962+13.25+\left(-13\right)\)

\(=-962+325+\left(-13\right)\)

\(=-650\)

Quy đồng mẫu số, ta đưa về dạng:

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