Question

Cho biết x/3=y/5; Tính B= 5x²+3y²/10x²-3y²

 

Answer 1

Đặt \(\frac{x}{3}=\frac{y}{5}=k\)

\(\Rightarrow x=3k;y=5k\)

Ta có:
\(B=\frac{5\cdot\left(3k\right)^2+3\left(5k\right)^2}{10\left(3k\right)^2-3\left(5k\right)^2}=\frac{45k^2+75k^2}{90k^2-75k^2}=\frac{120k^2}{15k^2}=8\)

Vậy B=8