Question

Answer 1

=> \(\dfrac{x+7}{x-3}=\dfrac{45}{15}\)

=>\(\dfrac{x+7}{x-3}=3\)

Answer 2

\(\dfrac{x+7}{45}=\dfrac{x-3}{15}\)

\(\Leftrightarrow\dfrac{x+7}{45}=\dfrac{3\left(x-3\right)}{45}\)

\(\Leftrightarrow x+7=3\left(x-3\right)\)

\(\Leftrightarrow x+7=3x-9\)

\(\Leftrightarrow-2x=-16\)

\(\Leftrightarrow x=8\)

Answer 3

khử mẫu

x+7=x-3

=>x+7-x+3=0

=>0+10=0(vô lí)

=>PT vô nghiệm