$\ I.)\quad49a^6+\square+100c^2=(\square+\square)^2$

Wende die 1. Binomische Formel an:

$\hspace{10mm}a^2+2ab+b^2\hspace{3.7mm}=\hspace{2mm} (a+b)^2$

$\quad49a^6+\boxed{140a^3c}+100c^2=\left(\boxed{7a^3}+\boxed{10c}\right)^2$

$\ II.)\quad(18ac+\square)\cdot (18ac-\square)=\square-\dfrac{1}{25}b^2$

Wende die 3. Binomische Formel an:

$\hspace{12mm}(a+b)\hspace{3mm}\cdot\hspace{3.5mm}(a-b)\hspace{9mm}=\hspace{10mm} a^2-b^2$

$\quad\left(18ac+\boxed{\dfrac{1}{5}b}\right)\cdot\left(18ac-\boxed{\dfrac{1}{5}b}\right)=\boxed{324a^2c^2}-\dfrac{1}{25}b^2$