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a fost răspuns

daca a3 +b=7 si a+3b=9 caculati

Răspuns :

Damian2604
3a+b=7
a+3b=9

3a+b=7
3a=7-b
a = [tex] \frac{7-b}{3} [/tex]

a+3b=9
[tex] \frac{7-b}{3} [/tex] +3b=9
amplificam 3b cu 3 ==> [tex] \frac{9b}{3} [/tex]=9
[tex] \frac{7-b}{3} [/tex]  +  [tex] \frac{9b}{3} [/tex]=9
[tex] \frac{7-b +9b}{3} [/tex]=9
7+8b /3 =9
8b/3=2
8b=2 x 3
8b=6
b =[tex] \frac{6}{8} [/tex]
3a+b=7
3a + 6/8 = 7
3a= 7 - 6/8
amplificam 7 cu 8
3a= [tex] \frac{56}{8} - \frac{6}{8} [/tex]
3a =[tex] \frac{50}{8} [/tex]
a = tex] \frac{50}{8} [/tex] : [tex] \frac{3}{1} [/tex]
a= [tex] \frac{50}{8} [/tex] x [tex] \frac{1}{3} [/tex]
a=[tex] \frac{50}{24} [/tex]
a= 25/12 dupa simplificarea cu 2

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