$$ \begin{aligned}-0.00033780617(x+15)(x+1)(x+1)(x-16)& \xlongequal{ }-(0x+0)(x+1)(x+1)(x-16) \xlongequal{ } \\[1 em] & \xlongequal{ }-(0x^2+0x+0x+0)(x+1)(x-16) \xlongequal{ } \\[1 em] & \xlongequal{ }-0(x+1)(x-16) \xlongequal{ } \\[1 em] & \xlongequal{ }-(0x+0)(x-16) \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}-(0x^2+0x+0x+0) \xlongequal{ } \\[1 em] & \xlongequal{ }-0\end{aligned} $$ | |
① | Multiply each term of $ \left( \color{blue}{0x0}\right) $ by each term in $ \left( x-16\right) $. $$ \left( \color{blue}{0x0}\right) \cdot \left( x-16\right) = 0x^2 \cancel{0x} \cancel{0x}0 $$ |