Răspuns:
[tex]\boldsymbol{a) \ \red{ 3\dfrac{4}{7} }} \ \boldsymbol{b) \ \red{ 4\dfrac{1}{2} }} \ \boldsymbol{c) \ \red{ 5\dfrac{11}{15} }} \ \boldsymbol{d) \ \red{ 4\dfrac{23}{28} }}[/tex]
[tex]\boldsymbol{e) \ \red{ 4\dfrac{2}{3} }} \ \boldsymbol{f) \ \red{ 1\dfrac{1}{6} }} \ \boldsymbol{g) \ \red{ 2\dfrac{10}{21} }} \ \boldsymbol{h) \ \red{ 1\dfrac{5}{12} }}[/tex]
Explicație pas cu pas:
[tex]a) \ 2\dfrac{1}{7} + 1\dfrac{3}{7} = 2 + \dfrac{1}{7} + 1 + \dfrac{3}{7} = 2 + 1 + \dfrac{1+3}{7} = 3 + \dfrac{4}{7} = \bf3\dfrac{4}{7}[/tex]
***
[tex]b) \ 1\dfrac{2}{5} + 3\dfrac{1}{10} = 1 + \dfrac{^{2)} 2}{5} + 3 + \dfrac{1}{10} = 1 + 3 + \dfrac{4}{10} + \dfrac{1}{10} = 4 + \dfrac{4+1}{10} = 4 + \dfrac{5^{(5} }{10} = \bf4\dfrac{1}{2}[/tex]
***
[tex]c) \ 3\dfrac{1}{3} + 2\dfrac{2}{5} = 3 + \dfrac{1}{3} + 2 + \dfrac{2}{5} = 3 + 2 + \dfrac{^{5)} 1}{3} + \dfrac{^{3)} 2}{5} = 5 + \dfrac{5+6}{15} = \bf5\dfrac{11}{15}[/tex]
***
[tex]d) \ 3\dfrac{5}{21} + 1\dfrac{7}{12} = 3 + \dfrac{^{4)} 5}{21} + 1 + \dfrac{^{7)} 7}{12} = 3 + 1 + \dfrac{20+49}{84} = 4 + \dfrac{69^{(3} }{84} = \bf4\dfrac{23}{28}[/tex]
***
[tex]e) \ 5\dfrac{5}{6} - 1\dfrac{1}{6} = 5 + \dfrac{5}{6} - \bigg(1 + \dfrac{1}{6}\bigg) = 5 + \dfrac{5}{6} - 1 - \dfrac{1}{6} = 5 - 1 + \dfrac{5 - 1}{6} = 4 + \dfrac{4^{(2} }{6} = \bf4\dfrac{2}{3}[/tex]
***
[tex]f) \ 4\dfrac{5}{18} - 3\dfrac{1}{9} = 4 + \dfrac{5}{18} - \bigg(3 + \dfrac{^{2)} 1}{9}\bigg) = 4 + \dfrac{5}{18} - 3 - \dfrac{2}{18} = 4 - 3 + \dfrac{5-2}{18} = 1 + \dfrac{3^{(3} }{18} = \bf1\dfrac{1}{6}[/tex]
***
[tex]g) \ 7\dfrac{1}{7} - 4\dfrac{2}{3} = \dfrac{49+1}{7} - \dfrac{12+2}{3} = \dfrac{^{3)} 50}{7} - \dfrac{^{7)} 14}{3} = \dfrac{150-98}{21} = \bf2\dfrac{10}{21}[/tex]
***
[tex]h) \ 9\dfrac{2}{3} - 8\dfrac{1}{4} = 9 + \dfrac{^{4)} 2}{3} - 8 - \dfrac{^{3)} 1}{4} = 9 - 8 + \dfrac{8}{12} - \dfrac{3}{12} = 1 + \dfrac{8-3}{12} = \bf1\dfrac{5}{12}[/tex]
