\(\frac{1}{3}-\frac{3}{4}-\left(-\frac{3}{5}\right)+\frac{1}{72}-\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)

\(=\frac{1}{3}-\frac{3}{4}+\frac{3}{5}+\frac{1}{72}-\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)

\(=\left(\frac{1}{3}-\frac{2}{9}\right)+\left(-\frac{3}{4}-\frac{1}{36}\right)+\left(\frac{3}{5}+\frac{1}{15}\right)+\frac{1}{72}\)

\(=\left(\frac{3}{9}-\frac{2}{9}\right)+\left(-\frac{27}{36}-\frac{1}{36}\right)+\left(\frac{9}{15}+\frac{1}{15}\right)+\frac{1}{72}\)

\(=\frac{1}{9}+\frac{-7}{9}+\frac{2}{3}+\frac{1}{72}\)

\(=-\frac{2}{3}+\frac{2}{3}+\frac{1}{72}\)

\(=0+\frac{1}{72}=\frac{1}{72}\)

Ta có :

\(A=\frac{1}{3}-\frac{3}{4}-\left(-\frac{3}{5}\right)+\frac{1}{72}-\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)

\(\Rightarrow A=\frac{5}{15}-\frac{54}{72}+\frac{9}{15}+\frac{1}{72}-\frac{16}{72}-\frac{1}{72}+\frac{1}{15}\)

\(\Rightarrow A=\left(\frac{5}{15}+\frac{9}{15}+\frac{1}{15}\right)+\left(-\frac{54}{72}+\frac{1}{72}-\frac{16}{72}-\frac{2}{72}\right)\)

\(\Rightarrow A=1-\frac{71}{72}=\frac{1}{72}\)

\(\frac{a}{b}+\frac{-a}{b}+1=\frac{a+\left(-a\right)}{b}+1=0+1=1\)

Câu tương tự có            

Bài làm

       \(\frac{1}{3}+\frac{3}{4}-\left(-\frac{3}{5}\right)+\frac{1}{72}+\frac{2}{9}-\left(-\frac{1}{36}\right)+\frac{1}{15}\)

\(=\frac{1}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{72}+\frac{2}{9}+\frac{1}{36}+\frac{1}{15}\)

\(=\left(\frac{1}{3}+\frac{3}{5}+\frac{1}{15}\right)+\left(\frac{1}{36}+\frac{3}{4}\right)+\left(\frac{1}{72}+\frac{2}{9}\right)\)

\(=\left(\frac{5}{15}+\frac{9}{15}+\frac{1}{15}\right)+\left(\frac{1}{36}+\frac{27}{36}\right)+\left(\frac{16}{72}+\frac{1}{72}\right)\)

\(=1+\frac{28}{36}+\frac{18}{72}\)

\(=\frac{36}{36}+\frac{28}{36}+\frac{9}{36}\)

\(=\frac{73}{36}\)

~ Không chắc có đúng hay không nx. ~
# Học tốt #

Sửa đề :

\(\frac{1}{3}+\frac{3}{4}-\left[-\frac{3}{5}\right]+\frac{1}{72}+\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)

\(=\frac{1}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{72}+\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)

\(=\left[\frac{1}{3}+\frac{3}{5}+\frac{1}{15}\right]-\left[\frac{3}{4}+\frac{2}{9}+\frac{1}{36}\right]+\frac{1}{72}\)

\(=\left[\frac{5}{15}+\frac{9}{15}+\frac{1}{15}\right]-\left[\frac{27}{36}+\frac{8}{36}+\frac{1}{36}\right]+\frac{1}{72}\)

\(=1-1+\frac{1}{72}=\frac{1}{72}\)

\(\frac{1}{3}-\frac{3}{4}-\frac{-3}{5}+\frac{1}{72}-\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)

\(=\left\{\frac{1}{3}+\frac{3}{5}+\frac{1}{15}\right\}\)\(-\left\{\frac{3}{4}+\frac{2}{9}+\frac{1}{36}\right\}\)\(+\frac{1}{72}\)

\(=1-1+1+\frac{1}{72}\)

\(=\frac{1}{72}\)

Bạn nhờ mik giúp thì phải nhớ tíck mik đó

A=1/3-3/4-(-3/5)+1/72-2/9-1/36+1/15

A=(1/3+3/5+1/15)-(3/4+2/9+1/36)+1/72

A=1-1+1+1/72=1/72

k mình nha