Suppose 
and 
. Then, what is the average (arithmetic mean) of the three products 
, 
, and 
?
+26367 Suppose and .
Then, what is the average (arithmetic mean) of the three products , , and ?
$$\small{\text{
$
\begin{array}{rcl}
(p+q+r)^2&=&(p+q+r)(p+q+r)=p^2+q^2+r^2+2(pq+qr+rp)\\
(p+q+r)^2&=&p^2+q^2+r^2+2(pq+qr+rp)\\
7^2&=&9+2(pq+qr+rp)\\
2(pq+qr+rp)&=&7^2-9=49-9=40\\
(pq+qr+rp) &=& 20
\end{array}
$
}}$$
the average (arithmetic mean) of the three products , , and ? $$\frac{(pq+qr+rp) }{3} = \frac{20}{3}=6\frac{2}{3}$$
+26367 Suppose and .
Then, what is the average (arithmetic mean) of the three products , , and ?
$$\small{\text{
$
\begin{array}{rcl}
(p+q+r)^2&=&(p+q+r)(p+q+r)=p^2+q^2+r^2+2(pq+qr+rp)\\
(p+q+r)^2&=&p^2+q^2+r^2+2(pq+qr+rp)\\
7^2&=&9+2(pq+qr+rp)\\
2(pq+qr+rp)&=&7^2-9=49-9=40\\
(pq+qr+rp) &=& 20
\end{array}
$
}}$$
the average (arithmetic mean) of the three products , , and ? $$\frac{(pq+qr+rp) }{3} = \frac{20}{3}=6\frac{2}{3}$$
