Question 862823
<pre><font face = "consolas" color = "indigo" size = 3><b>
Hi
(u+v)(u-v)= u^2 + v^2
u = 7i + j
u^2 = (7i + j)^2 = -49 + 14ij + j^2
v = i - 2j
v^2 = (i-2j)^2 = -1 - 4ij + 4j^2
-49 + 14ij + j^2
<u> -1 -  4ij + 4j^2</u>
 -50 + 10ij + 5j^2 
0r
5j^2 + 10ij - 50