Question

multiply the conjugates.
$left(\frac{1}{5}y + 6
ight)left(\frac{1}{5}y - 6
ight)=square$

Explanation:

Step1: Use difference - of - squares formula

The formula for $(a + b)(a - b)=a^{2}-b^{2}$. Here $a=\frac{1}{5}y$ and $b = 6$.

Step2: Square the terms

$(\frac{1}{5}y)^{2}-6^{2}=\frac{1}{25}y^{2}-36$.

Answer:

$\frac{1}{25}y^{2}-36$