on donne: a= 6/7 et b=4/7 Calculer: 1) a+b 2) a-b 3) ab on donne: a= 5/3 et b= 10/21 calculer:  1) a+b 2) a-b 3) ab grand merci par avance

Bonjour

[tex]a+b=\dfrac{6}{7}+\dfrac{4}{7}=\dfrac{10}{7}\\\\a-b=\dfrac{6}{7}-\dfrac{4}{7}=\dfrac{2}{7}\\\\a\times b=\dfrac{6}{7}\times\dfrac{4}{7}=\dfrac{24}{49}[/tex]

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[tex]a+b=\dfrac{5}{3}+\dfrac{10}{21}=\dfrac{35}{21}+\dfrac{10}{21}=\dfrac{45}{21}=\dfrac{15}{7}\\\\a-b=\dfrac{5}{3}-\dfrac{10}{21}=\dfrac{35}{21}-\dfrac{10}{21}=\dfrac{25}{21}\\\\a\times b=\dfrac{5}{3}\times\dfrac{10}{21}=\dfrac{50}{63}[/tex]

a=6/7      b=4/7
a+b=6/7+4/7=11/7
a-b=6/7-4/7=2/7
ab=6/7*4/7=24/49
  
a=5/3    b=10/21
a+b=5/3+10/21=30+105/21=135/21
a-b=5/3-10/21=105-30/21=75/21
ab=5/3*10/21=50/63