I believe the answer would be A. 2x-y=6 :)
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Answer:
A), B) and D) are true
Step-by-step explanation:
A) We can prove it as follows:

B) When you compute the product Ax, the i-th component is the matrix of the i-th column of A with x, denote this by Ai x. Then, we have that
. Now, the colums of A are orthonormal so we have that (Ai x)^2=x_i^2. Then
.
C) Consider
. This set is orthogonal because
, but S is not orthonormal because the norm of (0,2) is 2≠1.
D) Let A be an orthogonal matrix in
. Then the columns of A form an orthonormal set. We have that
. To see this, note than the component
of the product
is the dot product of the i-th row of
and the jth row of
. But the i-th row of
is equal to the i-th column of
. If i≠j, this product is equal to 0 (orthogonality) and if i=j this product is equal to 1 (the columns are unit vectors), then
E) Consider S={e_1,0}. S is orthogonal but is not linearly independent, because 0∈S.
In fact, every orthogonal set in R^n without zero vectors is linearly independent. Take a orthogonal set
and suppose that there are coefficients a_i such that
. For any i, take the dot product with u_i in both sides of the equation. All product are zero except u_i·u_i=||u_i||. Then
then
.
Answer:
15 hours
Step-by-step explanation:
is the number of hours that Liam volunteered in the first month
The next month he volunteered
times the time he volunteered the first month.
Total time he volunteered in the two months is 40 hours so

Time he volunteered in the first month is 15 hours.
Answer:
The table is show clearly in the figure attached.
P(boy if favourite activity is swimming) = 8/17 = 0.47
P(girl if favourite activity is sport) = 7/27 = 0.26
P(girl if favourite activity is reading) = 4/6 = 0.67
P(boy if favourite activity is sport) = 20/27 = 0.74
P(favourite activity is swimming if a girl) = 9/20 = 0.45
P(favourite activity is reading if a boy) = 2/30 = 0.07
P(favourite activity is swimming if a boy) = 8/30 = 0.27
P(favourite activity is reading if a girl) = 4/20 = 0.2