ta có:\(\frac{a}{3}\) =\(\frac{b}{5}\) =>\(\frac{3a}{9}\) =\(\frac{b}{5}\)
áp dụng t/c dãy tỉ số bằng nhau, ta có:
\(\frac{3a}{9}\) = \(\frac{b}{5}\) =\(\frac{3a-b}{9-5}\) =\(\frac{1}{2}\)
\(\frac{a}{3}\) = \(\frac{1}{2}\) => a=1,5
\(\text{Đặt }\dfrac{a}{3}=\dfrac{b}{5}=k\Rightarrow a=3k\) ; \(b=5k\)
Ta có : 3a + b = 2 => 3.3k + 5k = 2 => 9k + 5k = 2 => 14k = 2 => k = \(\dfrac{1}{7}\)
Do đó : \(\dfrac{a}{3}=\dfrac{1}{7}\Rightarrow a=\dfrac{1}{7}.3=\dfrac{3}{7}\)
\(\dfrac{b}{5}=\dfrac{1}{7}\Rightarrow b=\dfrac{1}{7}.5=\dfrac{5}{7}\)
Vậy a = \(\dfrac{3}{7}\) ; b = \(\dfrac{5}{7}\)
