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 

RELATED QUESTIONS

Please help me with this problem. Thank you.
Find the vectors u+v, u-v, and 5u-1/2.... (answered by MathLover1,ikleyn)

For u= i + j - 2k, v= 3i + j + 2k and w= 2i - 2j - 3k
Will someone please show me how to  (answered by Alan3354)

Could you help me solve this problem? I need to prove the identity... (answered by lwsshak3,Edwin McCravy)

U and V are two events. P(U_ = 0.64; P(V) = 0.36, and P(U AND V) = 0.18. Find P(U|V)... (answered by Boreal,ikleyn,greenestamps)

What is 
sin(u+v)+sin(u-v)/cos(u+v)+cos(u-v)=tan (u)

I have tried answering it:... (answered by Fombitz)

Find u * v and are these vectors orthogonal? If u = i+j and v =... (answered by ikleyn)

Consider the following.
u = i + 3j, v = −3i + j
(a) Find u · v
(b) Find the angle... (answered by MathLover1)

Consider the following.
u = i + 3j, v = −3i + j
(a) Find u · v.
(b) Find the angle... (answered by MathLover1)

Find the vectors 
u + v, u − v, and 5u − 1/2v.

(Simplify your answers... (answered by ikleyn)