\[\boxed{\text{541\ (541).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[1)\ (x - 2)^{2} - 4 =\]
\[= (x - 2 - 2)(x - 2 + 2) =\]
\[= x(x - 4)\]
\[2)\ (b + 7)^{2} - 100c^{2} =\]
\[= (b + 7 - 10c)(b + 7 + 10c)\]
\[3)\ 121 - (b + 7)^{2} =\]
\[= (11 - b - 7)(11 + b + 7) =\]
\[= (4 - b)(18 + b)\]
\[4)\ a^{4} - \left( 7b - a^{2} \right)^{2} =\]
\[= \left( 2a^{2} - 7b \right) \cdot 7b\]
\[5)\ (4x - 9)^{2} - (2x + 19)^{2} =\]
\[= (2x - 28)(6x + 10)\]
\[6)\ (a + b + c)^{2} - (a - b - c)^{2} =\]
\[= (2b + 2c) \cdot 2a =\]
\[= 4a \cdot (b + c)\]