a) \(\left(n-1\right)^2-\left(x-2\right)\left(x+2\right)=4\Leftrightarrow\left(n-1\right)^2=4+\left(x-2\right)\left(x+2\right)\)
\(\Leftrightarrow\left(n-1\right)^2=4+x^2-4\Leftrightarrow x^2=\left(n-1\right)^2\Rightarrow x=n-1\)
vậy \(x=n-1\)
b) \(3\left(x-1\right)-4\left(x-3\right)=6\left(x-1\right)\Leftrightarrow3x-3-4x+12=6x-6\)
\(\Leftrightarrow3x-3-4x+12-6x+6=0\Leftrightarrow-7x+15=0\Leftrightarrow7x=15\)
\(\Leftrightarrow x=\dfrac{15}{7}\) vậy \(x=\dfrac{15}{7}\)
c) \(\left(x+2\right)^2-x\left(x-3\right)=7\left(n+1\right)\Leftrightarrow x^2+4x+4-x^2+3x=7n+7\)
\(\Leftrightarrow7x+4=7n+7\Leftrightarrow7x=7n+7-4\Leftrightarrow7x=7n+3\Leftrightarrow x=\dfrac{7n+3}{7}\)
vậy \(x=\dfrac{7n+3}{7}\)
