Tap the blue circles to see an explanation.
$$ \begin{aligned}(x-5)(x+5)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}x^2+5x-5x-25 \xlongequal{ } \\[1 em] & \xlongequal{ }x^2+ \cancel{5x} -\cancel{5x}-25 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}x^2-25\end{aligned} $$ | |
① | Multiply each term of $ \left( \color{blue}{x-5}\right) $ by each term in $ \left( x+5\right) $. $$ \left( \color{blue}{x-5}\right) \cdot \left( x+5\right) = x^2+ \cancel{5x} -\cancel{5x}-25 $$ |
② | Combine like terms: $$ x^2+ \, \color{blue}{ \cancel{5x}} \, \, \color{blue}{ -\cancel{5x}} \,-25 = x^2-25 $$ |