Question

Fie a/b=3/7 . Valoarea raportului este 2a+3b/5a+2b

Answer 1

Răspuns:

a/b = 3/7 <=>

a/3 = b/7 = k

a = 3k, b = 7k

2a + 3b =

= 2*3k + 3*7k =

= 6k + 21k =

= 27k

5a + 2b =

= 5*3k + 2*7k =

= 15k + 14k =

= 29k

2a+3b / 5a+2b =

= 27k / 29k =

= 27/29

Answer 2

a/b = 3/7

(2a+3b)/(5a+2b) = x

2a+3b = x(5a+2b)

2a+3b = 5ax + 2bx ⎮:b

2•(a/b) + 3 = 5•(a/b)x + 2x

2•3/7 + 3 = 5•(3/7)x + 2x ⎮•7

6 + 21 = 15x + 14x

27 = 29x

⇒ x = 27/29