Step-by-step explanation:
There are 5 different positions of 666:
666////
/666///
//666//
///666/
////666
The forward dashes represent any number from 0 to 9.
Case 1: "666////"
Number of ways = 10⁴ = 10,000.
Case 2: The other positions.
Since the 1st forward dash cannot be 0 (leading digit),
Number of ways for each position = 9 * 10³ = 9,000
Number of ways for all 4 positions = 9,000 * 4 = 36,000.
Total evil numbers = 10,000 + 36,000 = 46,000.
Answer:
108
Step-by-step explanation:
- volume = area of the base * height
- Area of the base = 36 square inches .
- The height = 3 inches
- 36 * 3 = 108
Consider number 17. You know that
17=9+8.
Then for negative numbers you have the same rule (with respect to sign -):
-17=(-9)+(-8).
Since (-9)+9=9+(-9)=9-9=0, you have that
-17+9=(-9)+(-8)+9=(-9+9)+(-8)=0+(-8)=-8.
Answer: -17=(-9)+(-8).
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
.