Use Square of Difference: \({(a-b)}^{2}={a}^{2}-2ab+{b}^{2}\).
\[{x}^{2}-2x\times 10+{10}^{2}-x(x+80)\]
Expand by distributing terms.
\[{x}^{2}-2x\times 10+{10}^{2}-({x}^{2}+80x)\]
Remove parentheses.
\[{x}^{2}-2x\times 10+{10}^{2}-{x}^{2}-80x\]
Simplify \({10}^{2}\) to \(100\).
\[{x}^{2}-2x\times 10+100-{x}^{2}-80x\]
Simplify \(2x\times 10\) to \(20x\).
\[{x}^{2}-20x+100-{x}^{2}-80x\]
Collect like terms.
\[({x}^{2}-{x}^{2})+(-20x-80x)+100\]
Simplify.
\[-100x+100\]
-100*x+100
