Question

Aflați numerele a si b, știind ca sunt invers proporționale cu 0,2 si 0,5, iar 4a+3b=78

PLS! DAU COROANĂ!

Answer 1

{a, b} i.p. {0.2;0.5}
4a+3b=78
k-----constanta
0,2a=0.5b=k
0.2=2/10
0.5=5/10
2a/10=5b/10=k
2a/10=k⇒a=10k/2
5b/10=k⇒b=10k/5
 
 4a+3b=78
 4*10k/2+3*10k/5=78
40k/2+30k/5=78 (amplificam si aducem la acelasi numitor adica 10)
(200k+60k)/10=78
260k=78*10
260k=780
k=780/260
k=3⇒a=10k/2=10*3/2=30/2=15
         b=10k/5=10*3/5=30/5=6