Question

3 phần 7 +(âm 1 phần 5+ âm 3 phần 7

Answer 1

\(\dfrac{3}{7}+\left(-\dfrac{1}{5}+\dfrac{-3}{7}\right)\)

\(=\dfrac{3}{7}+\left(-\dfrac{7}{35}-\dfrac{15}{35}\right)\\ =\dfrac{3}{7}-\dfrac{22}{35}\\ =\dfrac{15}{35}-\dfrac{22}{35}\\ =-\dfrac{7}{35}\\ =-\dfrac{1}{5}\)

Answer 2

-1/5

tk nhe

Answer 3

\(\dfrac{3}{7}+\left(-\dfrac{1}{5}+\left(-\dfrac{3}{7}\right)\right)\\ =\dfrac{3}{7}+\left(\dfrac{-7}{35}+\dfrac{-15}{35}\right)\\ =\dfrac{3}{7}+\dfrac{-22}{35}\\ =\dfrac{15}{35}+\dfrac{-22}{35}=-\dfrac{7}{35}=-\dfrac{1}{5}\)

Answer 4

\(\dfrac{3}{7}+\left(\dfrac{-1}{5}+\dfrac{-3}{7}\right)=\dfrac{3}{7}+\dfrac{-3}{7}+\dfrac{-1}{5}=\dfrac{3+\left(-3\right)}{7}+\dfrac{-1}{5}=0+\dfrac{-1}{5}=\dfrac{-1}{5}\)