Question

se considera proportia a pe b egal 13 pe 4 determinati a si b in fiecare din cazurile
a-b=27      a+b=34        5a+2b=365
cu tot cu rezolvare ms

Answer 1

a/b=13/4⇒4a=13b⇒a=13b/4
a-b=27⇒13b/4-b=27 aducem la acelasi numitor⇒13b/4-4b/4=27⇒9b/4=27/1⇒9b=27·4⇒b=(27·4)/9 simplificam cu 9⇒b=3·4⇒b=12
a=13b/4=(13·12)/4 simplificam cu 4⇒a=13·3⇒a=39
2.a+b=34⇒13b/4+b=34⇒aducem la acelasi numitor 13b/4+4b/4=34⇒17b/4=34/1⇒17b=34·4⇒b=136/17⇒b=8
a=13b/4=(13·8)/4 simplificam cu 4⇒a=13·2=26⇒a=26
3.5a+2b=365⇒5·13b/4+2b=365⇒65b/4+2b=365, aducem la acelasi numitor si avem
65b/4+8b/4=365⇒73b/4=365/1⇒53b=365·4⇒b=1460/73⇒b=20
a=13b/4=13·20/4 simplificam⇒a=65
succes