Question

$$( { x }^{ 2 } -1)( { x }^{ 2 } +5x-6)=0$$

Answer

x=-1,1,-6

Solution


Rewrite \({x}^{2}-1\) in the form \({a}^{2}-{b}^{2}\), where \(a=x\) and \(b=1\).
\[({x}^{2}-{1}^{2})({x}^{2}+5x-6)=0\]
Use Difference of Squares: \({a}^{2}-{b}^{2}=(a+b)(a-b)\).
\[(x+1)(x-1)({x}^{2}+5x-6)=0\]
Factor \({x}^{2}+5x-6\).
\[(x+1)(x-1)(x-1)(x+6)=0\]
Solve for \(x\).
\[x=-6,\pm 1\]