Question

1.Calculati media aritmetica a numerelor:
a) 1/3 si 5/7
b)3/4, 5/6 si 2/7

2.Media aritmetica a doua numere este 1/5, iar unul din numere este 1/2. Aflati celalalt numar.

VA ROG E URGENT!

Answer 1

1. Rezolvăm exercițiul folosind formula :[tex] m_{a} = \frac{a+b}{2} = \frac{a+b+c}{3} \\ a). \frac{ \frac{1}{3} + \frac{5}{7} }{2} = \frac{ \frac{7}{21} + \frac{15}{21} }{2} = \frac{ \frac{22}{21} }{2} = \frac{22}{21} : 2 = \frac{22}{21} * \frac{1}{2} = \frac{22}{42} = \frac{11}{21} \\ b). \frac{ \frac{3}{4} + \frac{5}{6} + \frac{2}{7} }{3} = \frac{ \frac{63+70+24}{84} }{3} = \frac{ \frac{157}{84} }{3}= \frac{157}{84} : 3= \frac{157}{84} * \frac{1}{3} = \frac{157}{252} \\ 2. a- numarul necunoscut \\ m_{a} = \frac{a+ \frac{1}{2} }{2} = 1/5 [/tex]→2a+1/4=1/5 →5(2a+1)=1/5→10a+5=1/5→10a=-1→a=-1/10→a=-0.1