FOIL 법을 사용하여 $$$\left(x + 1\right) \left(x + 1\right)$$$을(를) 곱하세요

FOIL 방법을 사용하여 $$$\left(x + 1\right) \left(x + 1\right)$$$을 전개하세요.

$$$\left({\color{red}\left(x\right)} + {\color{purple}\left(1\right)}\right) \left({\color{green}\left(x\right)} + {\color{blue}\left(1\right)}\right) = \underbrace{{\color{red}\left(x\right)} {\color{green}\left(x\right)}}_{\text{처음}} + \underbrace{{\color{red}\left(x\right)} {\color{blue}\left(1\right)}}_{\text{외부}} + \underbrace{{\color{purple}\left(1\right)} {\color{green}\left(x\right)}}_{\text{내부}} + \underbrace{{\color{purple}\left(1\right)} {\color{blue}\left(1\right)}}_{\text{마지막}} = x^{2} + x + x + 1 = x^{2} + 2 x + 1$$$

$$$\left(x + 1\right) \left(x + 1\right) = x^{2} + 2 x + 1$$$A