Question

tìm x 
a) 0,5/0,7=0,1/5x
b) 16/x=x/25
c) x-2/6=4/3
d) 16/x^2= x/4

Answer 1

a: =>5x=0,7x0,1/0,5=7/50

=>x=7/250

b: =>x²=400

=>x=20 hoặc x=-20

c: =>x-2=8

=>x=10

d: =>x³=64

=>x=4

Answer 2

a, \(\dfrac{\dfrac{5}{10}}{\dfrac{7}{10}}=\dfrac{\dfrac{1}{10}}{5x}\Rightarrow\dfrac{5}{7}=\dfrac{1}{50x}\Leftrightarrow250x=7\Leftrightarrow x=\dfrac{7}{250}\)đk x khác 0

b, \(x^2=25.16\Leftrightarrow\left[{}\begin{matrix}x=\sqrt{25.16}\\x=-\sqrt{25.16}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=5.4=20\\x=-6.4=-20\end{matrix}\right.\)

c, \(3x-6=24\Leftrightarrow3x=30\Leftrightarrow x=10\)

d, \(x^3=64\Leftrightarrow x=4\)

Answer 3

a.

=> \(x=0,1:\left(\dfrac{0,5}{0,7}\right):5=\dfrac{7}{250}\)

b.

\(\dfrac{16}{x}=\dfrac{x}{25}\)

=> \(\dfrac{400}{25x}=\dfrac{x^2}{25x}\)

=> 400 = x^2

=> x = -20 hoặc 20

c.

=> \(x=\dfrac{4}{3}+\dfrac{2}{6}=\dfrac{5}{3}\)

d.

\(\dfrac{16}{x^2}=\dfrac{x}{4}\)

<=> \(\dfrac{64}{4x^2}=\dfrac{x^3}{4x^2}\)

=> x^3 = 64

=> x = -4 hoặc = 4