Răspuns :

PutereDinuid

[tex]\frac{a}{b}=\frac{3}{7} \ \ \Rightarrow a= \frac{3b}{7} \\ \Rightarrow \ \frac{a+b}{b-a} =\frac{\frac{3b}{7}+b}{b-\frac{3b}{7}}=\frac{\frac{3b}{7}+\frac{7b}{7}}{\frac{7b}{7}-\frac{3b}{7}}= \frac{10b}{7}:\frac{4b}{7}=\frac{5b}{2b}=\boxed{\frac{5}{2}}[/tex]

Chris02Juniorid

Răspuns:

2 1/2

Explicație pas cu pas:

a/b = 3/7 si aplicam proprietatile proportiilor:

a+b / b-a = 3+7 / 7-3 = 10/4 = 5/2 = 2 1/2.

Sau

Metoda2:

a = 3b/7

3b/7 + b / b - 3b/7 = 3b+7b / 7b-3b = 10/4 = 5/2 = 2 1/2.

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