Question

a)\(\frac{2,1}{x}=\frac{1,4}{-5}\) b)\(\frac{2}{x-1}=\frac{16}{15}\) c)\(\frac{20}{x}=\frac{x}{5}\)

Answer 1

GIÚP MÌNH VỚI

Answer 2

Bạn nhân chéo lại nhé

A, 2.1.(-5)=1.4.x (bạn tự tính nhé)

B, x-1.16=15.2

C, x.x=20.5

=x mũ 2=100

x=5mũ 2

Answer 3

a) \(\frac{2,1}{x}=\frac{1,4}{-5}\)

\(\Rightarrow2,1.\left(-5\right)=x.1,4\)

\(\Rightarrow-10,5=x.1,4\)

\(\Rightarrow x=\left(-10,5\right):1,4\)

\(\Rightarrow x=-7,5\)

Vậy \(x=-7,5.\)

b) \(\frac{2}{x-1}=\frac{16}{15}\)

\(\Rightarrow2.15=\left(x-1\right).16\)

\(\Rightarrow30=16x-16\)

\(\Rightarrow16x=30+16\)

\(\Rightarrow16x=46\)

\(\Rightarrow x=46:16\)

\(\Rightarrow x=\frac{23}{8}\)

Vậy \(x=\frac{23}{8}.\)

c) \(\frac{20}{x}=\frac{x}{5}\)

\(\Rightarrow20.5=x.x\)

\(\Rightarrow100=x^2\)

\(\Rightarrow x^2=100\)

\(\Rightarrow\left[{}\begin{matrix}x=10\\x=-10\end{matrix}\right.\)

Vậy \(x\in\left\{10;-10\right\}.\)

Chúc bạn học tốt!