a) \(\frac{x-5}{7}=\frac{5}{3}\)
\(\Rightarrow\left(x-5\right)\cdot3=7\cdot5\)
\(\Rightarrow3x-15=35\)
\(\Rightarrow3x=15+35\)
\(\Rightarrow3x=50\)
\(\Rightarrow x=\frac{50}{3}\)
b) \(\frac{x-3}{3}=\frac{12}{x-3}\)
\(\Rightarrow\left(x-3\right)\cdot\left(x-3\right)=3\cdot12\)
\(\Rightarrow\left(x-3\right)^2=36\)
\(\Rightarrow\left(x-3\right)^2=6^2\)hoặc \(\left(x-3\right)^2=\left(-6\right)^2\)
\(\Rightarrow x-3=6\) \(x-3=-6\)
\(\Rightarrow x=6+3\) \(x=-6+3\)
\(\Rightarrow x=9\) hoặc \(x=-3\)
c) \(\frac{5-2x}{4}=\frac{7}{3}\)
\(\Rightarrow\left(5-2x\right)\cdot3=4\cdot7\)
\(\Rightarrow15-6x=28\)
\(\Rightarrow6x=15-28\)
\(\Rightarrow6x=-13\)
\(\Rightarrow x=-\frac{13}{6}\)
d) \(\frac{x+1}{4}=\frac{7}{3}\)
\(\Rightarrow\left(x+1\right)\cdot3=2\cdot7\)
\(\Rightarrow3x+3=28\)
\(\Rightarrow3x=28-3\)
\(\Rightarrow3x=25\)
\(\Rightarrow x=\frac{25}{3}\)
Chúc bạn học tốt !!!
