\(12x+69-23=109\)

\(\Rightarrow12x+46=109\)

\(\Rightarrow12x=63\)

\(\Rightarrow x=\frac{63}{12}\)

\(\Rightarrow x=5,25\)

b) \(\frac{56}{x}+49=7\)

\(\Rightarrow\frac{56}{x}=-42\)

\(\Rightarrow-42x=56\)

\(\Rightarrow x=\frac{-4}{3}\)

\(\frac{\sqrt{x}+1}{\sqrt{x}-1}\)

\(=\frac{\sqrt{x}-1+2}{\sqrt{x}-1}\)

=\(\frac{\sqrt{x}-1}{\sqrt{x}-1}+\frac{2}{\sqrt{x}-1}\)

\(=1+\frac{2}{\sqrt{x}-1}\)

đề biểu thức có nghiệm nguyên thì \(\sqrt{x}-1\inƯ\left(2\right)\)

\(\Rightarrow\sqrt{x}-1\in\left(1,-1,-2,2\right)\)

\(\sqrt{x}-1=2\)

\(\Leftrightarrow x=9\)(chọn)

\(\sqrt{x}-1=-1\)

\(\Leftrightarrow x=4\) (chọn)