Question

Aflati numerel a si b stiind ca sunt direct proportionale cu 2 si 3,iar a+b=25

Answer 1

{a,b} d.p. {2,3}

a/2=b/3⇒a/b=2/3

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

25/b=5/3⇒ 5/b=1/3

b = 5 ×3 =1 5

a = 2b/3 = 30/3 = 10

deci a = 10 si b = 15

Answer 2

Met 1:

a/2=b/3=k

a=2k

b=3k

a+b=5k=25

k=5

a=10

b=15.

sau

Met 2:

a/2=b/3

a/b=2/3

a/ a+b = 2/ 2+3

a/25 = 2/5

a/5 = 2

a=10

b=3a/2=30/2=15

ar mai fi o metoda, prin substitutie

Met 3:

a=2b/3

a+b=2b/3 + b = 25

2b+3b = 75

5b=75

b=75:5=15

a=2*15 / 3= 2*5 = 10.