SOLUTION: assuming u = 7 i + j , v = i - 2 j (u+v)*(u-v) Can someone show me how to do this, the book is extremely confusing. Thank you

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Question 862823: assuming u = 7 i + j , v = i - 2 j
(u+v)*(u-v)
Can someone show me how to do this, the book is extremely confusing. Thank you
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


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

 -1 -  4ij + 4j^2

 -50 + 10ij + 5j^2 

0r

5j^2 + 10ij - 50