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:
3
Step-by-step explanation:
The number is 3.
Step-by-step explanation:
Finding the Number
To find the number, we have to translate the problem above to an algebraic equation. The algebraic equation refers to the statement of the equality of two algebraic expressions.
Equation:
Let "x" be the number.
4 is divided by a number - 4/x
3 divided by the number decreased by 2 - 3/x-2
"4 is divided by a number is equal to 3 divided by the number decreased by 2"
4/x = 3/x-2
Solution:
Cross multiply.
4/x = 3/x-2
x(3) = 4(x-2)
3x = 4x - 8
(Combine similar terms.)
3x - 4x = - 8
- x = - 8
- x/- 1 = - 8/- 1
x = 8
Final Answer:
8
Checking:
4/x = 3/x-2
4/8 = 3/8-2
1/2 = 3/6
1/2 = 1/2 ✔
Answer:
125/28
4.46428571
4 13/28
There all right
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