Can you post your work so we can check it?
Consider vectors v1, v2, v3 in R^4; we are told that (vi dot vj) is the entry aij of matrix A. A =
[3 5 11]
[5 9 20]
[11 20 49].
Find length of (v1 + v2). For this I got 2(sqrt(3)). Can someone check this?
Also, find projV(v3), where V = span(v1, v2). Express your answer as a linear combination of v1 and v2.