Вправа 555 алгебра Бевз гдз 7 клас
$$\begin{aligned}
&\text { № } 555\\
&\begin{aligned}
& \text { a) }(a-2)(a+2)\left(a^2+4\right)-\left(a^2-2\right)^2=\left(a^2-4\right)\left(a^2+4\right)-\left(a^2-2\right)^2= \\
& =a^4-16-a^4+4 a^2-4=4 a^2-20
\end{aligned}\\
&\begin{aligned}
& \text { б) } a^4 b^4-(a b-c)(a b+c)\left(a^2 b^2+c^2\right)=a^4 b^4-\left(a^2 b^2-c^2\right)\left(a^2 b^2+c^2\right)= \\
& =a^4 b^4-a^4 b^4+c^4=c^4
\end{aligned}\\
&\begin{aligned}
& \text { B) }\left(3 x^2+y\right)\left(3 x^2-y\right)\left(9 x^4+y^2\right)-9\left(9 x^8-y^4\right)=\left(9 x^4-y^2\right)\left(9 x^4+y^2\right)- \\
& -81 x^8+9 y^4=81 x^8-y^4-81 x^8+9 y^4=8 y^4
\end{aligned}\\
&\text { г) } \frac{1}{16}-\left(\frac{1}{2}-3 a^2 b\right)\left(\frac{1}{2}+3 a^2 b\right)\left(\frac{1}{4}+9 a^4 b^2\right)=\\
&=\frac{1}{16}-\left(\frac{1}{4}-9 a^4 b^2\right)\left(\frac{1}{4}+9 a^4 b^2\right)=\\
&=\frac{1}{16}-\frac{1}{16}+81 a^8 b^4=81 a^8 b^4
\end{aligned}
$$
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