\(\frac35+\frac{7}{10}=\frac{6}{10}+\frac{7}{10}=\frac{6+7}{10}=\frac{13}{10}\)

\(\frac56-\frac29=\frac{45}{54}-\frac{12}{54}=\frac{45-12}{54}=\frac{33}{54}=\frac{11}{18}\)

\(\frac34-\frac52=\frac34-\frac{10}{4}=\frac{3-10}{4}=-\frac74\)

\(2+\frac57=\frac{14}{7}+\frac57=\frac{14+5}{7}=\frac{19}{7}\)

\(\frac{13}{5}-2=\frac{13}{5}-\frac{10}{5}=\frac{13-10}{5}=\frac35\)

câu 3 sai à sao 3-10 đc

?

a. 5

b. 607

c. 30

d.50 600

cái đầu sai đề à ?

\(6m^27dm^2=6,07dm^2\)

\(\frac{3}{10}m^2=30dm^2\)

\(\frac{7}{10}dm^2=70cm^2\)

\(5m^2600cm^2=50600cm^2\)

\(\frac{2}{3}\div\frac{x}{5}+\frac{5}{7}=\frac{2}{7}\div\frac{3}{5}+\frac{10}{9}\)

\(\frac{2}{3}\div\frac{x}{5}+\frac{5}{7}=\frac{10}{21}+\frac{10}{9}\)

\(\frac{2}{3}\div\frac{x}{5}+\frac{5}{7}=\frac{300}{189}\)

\(\frac{2}{3}\div\frac{x}{5}=\frac{300}{189}-\frac{5}{7}\)

\(\frac{2}{3}\div\frac{x}{5}=\frac{55}{63}\)

\(\frac{x}{5}=\frac{2}{3}\div\frac{55}{63}\)

\(\frac{x}{5}=\frac{42}{55}\)

\(x=42\div\left(55\div5\right)=\frac{42}{11}\)

quy đồng lên có thế x phải hỏi

từ 1 đến 28 có 28 số hạng mà cách nhau 3 đơn vị nên có 10 số hạng

suy ra  có 10 số x

=10x+1+4+7+...........+28

số số hạng từ 1 đén 28 là

[28-1];3+1=10 số hạng

tổng là;[28+1]x10;2=145

=10x+145=195

10x=195-145

10x=50

x=5

\(3\frac{3}{4}\times4=\frac{3\times4+3}{4}\times4=\frac{15}{4}\times4=\frac{15\times4}{4}=15\)

\(4\frac{3}{2}\div1\frac{1}{2}=\frac{4\times2+3}{2}\div\frac{1\times2+1}{2}=\frac{11}{2}\div\frac{3}{2}=\frac{11}{2}\times\frac{2}{3}=\frac{11}{3}\)

\(4\frac{3}{4}+2\frac{3}{2}=\frac{4\times4+3}{4}+\frac{2\times2+3}{2}=\frac{19}{4}+\frac{7}{2}=\frac{19}{4}+\frac{14}{4}=\frac{33}{4}\)

\(3\frac{8}{6}-4\frac{1}{3}=\frac{3\times8+6}{6}-\frac{4\times3+1}{3}=\frac{30}{6}-\frac{13}{3}=\frac{30}{6}-\frac{26}{6}=\frac{4}{6}=\frac{2}{3}\)

\(3\frac{2}{4}\)x 4 = \(\frac{14}{4}\)x 4 = \(\frac{56}{4}\)

\(4\frac{3}{2}\): \(1\frac{1}{2}\)= \(\frac{11}{2}\): \(\frac{3}{2}\)= \(\frac{11}{2}\)x \(\frac{2}{3}\)= \(\frac{22}{6}\)= \(\frac{11}{3}\)

\(4\frac{3}{4}\)+ \(2\frac{3}{2}\)= \(\frac{11}{4}\)+ \(\frac{7}{2}\)= \(\frac{25}{4}\)= 6,25

\(3\frac{8}{6}\)- \(4\frac{1}{3}\)= \(\frac{13}{3}\)- \(\frac{13}{3}\)= 0