Răspuns:
Explicație pas cu pas:
Primul mod:
a/b = 3/5 ⇒ 5 × a = 3 × b → produsul mezilor = produsul extremilor
b = ( 5 × a ) / 3
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( 3 a - b ) / ( 2 a - b ) = 4
= ( 3 a - 5a/3 ) / ( 2 a - 5a/3 ) =
= ( 9 a/3 - 5a/3) / ( 6a /3 - 5a/3 ) =
= ( 4 a/3 ) / (a/3) =
= ( 4 a / 3 ) × ( 3/a) =
= 4
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al II-lea mod:
a/b = 3/5 ⇒ a/3 = b/5 = k ⇒ a = 3 k si b = 5 k
( 3 a - b ) / ( 2 a - b ) = 4
= ( 3 × 3 k - 5 k ) / ( 2 × 3 k - 5 k ) =
= ( 9 k - 5 k ) / ( 6 k - 5 k ) =
= 4 k / k =
= 4
