\(\frac{5x-2y}{3x+4y}=\frac{3}{4}\Rightarrow9x+12y=20x-8y\)

\(\Rightarrow11x=20y\)

\(\Rightarrow\frac{x}{y}=\frac{20}{11}\)

20/11 can cach lam kb nhac cho 

k nua nha

\(\frac{5x-2y}{3x+4y}=\frac{3}{4}\)

\(=>\left(5x-2y\right).4=\left(3x+4y\right).3\)

\(=>20x-8y=9x+12y\)

\(=>20x-9x=12y+8y\)

\(=>11x=20y\)

\(=>\frac{x}{y}=\frac{20}{11}\)

vay \(\frac{x}{y}=\frac{20}{11}\)

\(\frac{5x-2y}{3x+4y}=\frac{3}{4}\Rightarrow\left(5x-2y\right).4-3\left(3x+4y\right)=0\)

\(\Rightarrow20x-8y-9x-12y=0\)

\(\Rightarrow11x-20y=0\)

\(\Rightarrow11x=20y\)

\(\Rightarrow\frac{x}{y}=\frac{20}{11}\)

từ tỉ lệ thức đã cho ta có;

4(5x-2y)=3(3x+4y)

20x-8y=9x+12y

11x-8y=12y

11x=20y

x/y=20/11

Ta có : \(\dfrac{5x-2y}{3x+4y}=\dfrac{3}{4}\)

\(\Leftrightarrow4\left(5x-2y\right)=3\left(3x+4y\right)\)

\(\Leftrightarrow20x-8y=9x+12y\)

\(\Leftrightarrow11x-20y=0\)

\(\Leftrightarrow11x=20y\)

Áp dụng tính chất tỉ lệ thức ta có :

\(11x=20y\Leftrightarrow\dfrac{x}{y}=\dfrac{20}{11}\)

Vậy .......

Ta có : \(\dfrac{5x-2y}{3x+4y}=\dfrac{3}{4}\)

\(\Rightarrow3\left(3x+4y\right)=4\left(5x-2y\right)\)

\(\Rightarrow9x+12y=20x-8y\)

\(\Rightarrow9x=20x-20y\)

\(\Rightarrow11x=20y\)

\(\Rightarrow\dfrac{x}{20}=\dfrac{y}{11}\)'\(\Rightarrow x:y=11:20=\dfrac{11}{20}\)

5x - 2y/3x + 4y = 3/4

=> (5x - 2y) × 4 = (3x + 4y) × 3

=> 20x - 8y = 9x + 12y

=> 20x - 9x = 12y + 8y

=> 11x = 20y

=> x/y = 20/11

từ tỉ lệ thức ta có

4(5x-2y)=3(3x+4y)

20x-8y=9x+12y

11x-8y=12y

11x=20y

x/y=20/11

bạn giải đi bạn

Theo đề ta có: \(x:y:z=3:4:5\Rightarrow\frac{x}{3}=\frac{y}{4}=\frac{z}{5}\)

Đặt: \(\frac{x}{3}=\frac{y}{4}=\frac{z}{5}=k\left(k\inℕ^∗\right)\)

Suy ra: \(x=3k;y=4k;z=5k\) Thay vào biểu thức P ta có:

\(P=\frac{3k+8k+15k}{6k+12k+20k}+\frac{6k+12k+20k}{9k+16k+25k}+\frac{9k+16k+25k}{12k+20k+30k}\)

\(P=\frac{26k}{38k}+\frac{38k}{50k}+\frac{50k}{62k}=\frac{13}{19}+\frac{19}{25}+\frac{25}{31}=\frac{33141}{14725}\)

\(\Rightarrow4\left(3x+5y\right)=x-2y\Rightarrow12x+20y=x-2y\Rightarrow11x=-22y\Rightarrow\frac{x}{y}=\frac{-22}{11}=-2\)

\(\frac{3x+5y}{x-2y}=\frac{1}{4}\)

\(\Rightarrow x-2y=4\left(3x+5y\right)\)

\(\Rightarrow x-2y=12x+20y\)

\(\Rightarrow12x-x=20y+2y\)

\(\Rightarrow11x=22y\)

\(\Rightarrow x=2y\Leftrightarrow\frac{x}{y}=2\)