Question

tìm x biết

a,\(\dfrac{x}{13}=\dfrac{35}{91}\)

b,\(\dfrac{9+x}{13-x}=\dfrac{5}{6}\)

c,\(x+x:5\cdot7,5+x:2\cdot9=315\)

Answer 1

a, \(\dfrac{x}{13}=\dfrac{35}{91}\Leftrightarrow\dfrac{x}{13}=\dfrac{5}{13}\Leftrightarrow x=5\)

b, \(\dfrac{9+x}{13-x}=\dfrac{5}{6}\Leftrightarrow\dfrac{9+x}{13-x}=\dfrac{10}{12}\Leftrightarrow x=1\)

@đỗ hương giang

Answer 2

a.

\(\dfrac{x}{13}=\dfrac{35}{91}\)

\(\Rightarrow x=\dfrac{35.13}{91}=5\)

Vậy x = 5

b.

\(\dfrac{9+x}{13-x}=\dfrac{5}{6}\)

\(\Rightarrow\dfrac{9+x}{13-x}=\dfrac{10}{12}\)

\(\Rightarrow\dfrac{x=10-9}{13-12=x}\Rightarrow x=\dfrac{1}{1}=1\)

Vậy x =1

c.

x + x : 5 . 7,5 + x : 2.9 = 315

\(\Rightarrow x+\dfrac{x}{5}7,5+\dfrac{x}{2}9=7x\)

\(\Rightarrow7x=3^3.5\)

\(\Rightarrow7x=135\)

\(\Rightarrow x=\dfrac{135}{7}\)

Vậy x = \(\dfrac{135}{7}\)

Chúc bạn học tốt!!!