Question

Alfati doua numere a si b stiind ca sunt direct proportionale cu 2 si 9 si produsul lor este 72

Answer 1

{a;b} d.p. {2;9} => a/2=b/9=k
a/2=k=> a=2k
b/9=k=> b=9k
a*b=72
2k*9k=72
18k²=72
k²= 72/18
k²=4
√k²=√4
k=2
a=2k=> a=4
b=9k=> b=18

Answer 2

{a;b}d.p.{2;9} => a/2=b/9=k => a=2k si b=9k.Mai stiim ca: a•b=72 <=> 2k•9k=72 <=> 18•k^2=72 =>k^2=72:18=4 =>k^2=4 ; 2^2=4 => k=2.Atunci a=2k=2•2=4 si b=9k=9•2=18.