Use algebra tiles to find $\left(7 x^2-8\right)-\left(2 x^2+2 x-1\right)$.
$x^2$$x^2$ $x^2$ \multicolumn{2}{|r|}{$x^2$}
\multirow{3}{*}{$x^2$}\multirow{3}{*}{$x^2$} \multirow{3}{*}{$x^2$} -1 -1
-1 -1
-1 -1
Combine like terms. For example, write 3 instead of $1+1+1$.
$x^2$ | $x^2$ | $x^2$ | \multicolumn{2}{|r|}{$x^2$} | |
\multirow{3}{*}{$x^2$} | \multirow{3}{*}{$x^2$} | \multirow{3}{*}{$x^2$} | -1 | -1 |
| -1 | -1 | |||
| -1 | -1 | |||