Question

Tìm x:

a) \(\frac{x}{7}\) = \(\frac{x+16}{35}\)

b) \(\frac{2-x}{16}\) = \(\frac{-4}{x-2}\)

c) \(\frac{14}{x}\) = \(\frac{x-1}{4}\)

Answer 1

\(a.\frac{x}{7}=\frac{x+16}{35}\)

\(\Rightarrow35x=7\left(x+16\right)\)

\(\Rightarrow35x=7x+112\)

\(\Rightarrow35x-7x=112\)

\(\Rightarrow28x=112\)

\(\Rightarrow x=112:28\)

\(\Rightarrow x=4\)

\(b.\frac{2-x}{16}=\frac{-4}{x-2}\)

\(\Rightarrow\frac{-\left(x-2\right)}{16}=\frac{-4}{x-2}\)

\(\Rightarrow\frac{x-2}{16}=\frac{4}{x-2}\)

\(\Rightarrow\left(x-2\right)^2=4.16\)

\(\Rightarrow\left(x-2\right)^2=64\)

\(\Rightarrow\left(x-2\right)^2=\left(\pm8\right)^2\)

\(\Rightarrow x-2=8\) hoặc \(x-2=-8\)

+) Nếu \(x-2=8\)

\(\Rightarrow x=8+2\)

\(\Rightarrow x=10\)

+) Nếu \(x-2=-8\)

\(\Rightarrow x=-8+2\)

\(\Rightarrow x=-6\)

Vậy \(x=10;x=-6\)

Answer 2

a) \(\frac{x}{7}=\frac{x+16}{35}\)

\(\Rightarrow35.x=7.\left(x+16\right)\)

\(\Rightarrow35.x=7.x+7.16\)

\(\Rightarrow35x=7x+112\)

\(\Rightarrow35x-7x=112\)

\(\Rightarrow28x=112\)

\(\Rightarrow x=4\)

Vậy .............

Answer 3

a) \(\frac{x}{7}=\frac{x+16}{35}\)

\(\Rightarrow\) x.35 = 7.(x + 16)

x.35 = 7x + 7.16

x.35 = 7x + 112

x.35 - 7x = 112

x.(35 - 7) = 112

x.28 = 112

x = 112 : 28

x = 4

b), c) tương tự