Question

a,  \(\frac{x}{4}\)= \(\frac{21}{28}\)

b,   \(\frac{2x}{5}\)= \(\frac{-24}{10}\)

tìm x, nhanh giùm mik nha

ai nhanh nhất đúng nhất thì mik tick

Answer 1

a) \(\frac{x}{4}=\frac{21}{28}\Rightarrow\frac{x}{4}=\frac{3}{4}\Rightarrow x=3\)

Vậy x = 3

b) \(\frac{2x}{5}=\frac{-24}{10}\Rightarrow\frac{2x}{5}=\frac{-12}{5}\Rightarrow2x=-12\Rightarrow x=-6\)

Vậy x = -6

Answer 2

\(a)\frac{x}{4}=\frac{21}{28}\)

\(\Rightarrow x\cdot28=4\cdot21\)

\(\Rightarrow x\cdot28=84\)

\(\Rightarrow x=3\)

\(b)\frac{2x}{5}=\frac{-24}{10}\)

Rút gọn : \(\frac{2x}{5}=\frac{-12}{5}\)

\(\Rightarrow2x=-12\)

\(\Rightarrow x=(-12)\div2=-6\)

Answer 3

a, \(\frac{x}{4}=\frac{21}{28}\)

Ta có : x . 28 = 4. 21

                  x = \(\frac{21.4}{28}\)

                  x = 3

b, \(\frac{2x}{5}=\frac{-24}{10}\)

Ta có : 2x . 10 = 5 . (-24)

                   2x = \(\frac{5.\left(-24\right)}{10}\)

                   2x = -12

                     x = -12 : 2

                     x = -6