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Linear Algebra

Linear algebra is the detailed study of vector spaces. With applications in such disparate fields as sociology, economics, computer programming, chemistry, and physics, including its essential role in mathematically describing quantum mechanics and the theory of relativity, linear algebra has become one of the most essential mathematical disciplines for the modern world. Please direct all questions regarding matrices, determinants, eigenvalues, eigenvectors, and linear transformations into this category.

500 Questions

How many solution sets do systems of linear inequalities have. Must solutions to systems of linear inequalities satisfy both inequalities. In what case might they not?

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Asked by Wiki User

There is only one solution set. Depending on the inequalities, the set can be empty, have a finite number of solutions, or have an infinite number of solutions. In all cases, there is only one solution set.

What is the product of -a and -b?

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Asked by Wiki User

Negative times negative equals positve, so -a*-b=ab (positive ab)

Is null square matrix a skew symmetric?

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Asked by Wiki User

yes, it is both symmetric as well as skew symmetric

How do you Write a C program for matrix?

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Asked by Wiki User

/* multiplication of a 3*3 matrix*/

#include<stdio.h>

main()

{

int a[3][3],b[3][3],c[3][3];

int i,j,k;

printf("enter the elements in A matrix:\n");

for(i=0;i<=2;i++)

{

for(j=0;j<=2;j++)

{

scanf("%d",&a[i][j]);

}

}

printf("enter b matrix:\n");

for(i=0;i<=2;i++)

{

for(j=0;j<=2;j++)

{

scanf("%d",&b[i][j]);

}

}

for(i=0;i<=2;i++)

{

printf("\n");

for(j=0;j<=2;j++)

{

c[i][j]=0;

for(k=0;k<=2;k++)

{

c[i][j] = c[i][j]+a[i][k] * b[k][j];

}

}

}

printf("multiplication matrix is:\n");

for(i=0;i<=2;i++)

{

for(j=0;j<=2;j++)

{

printf("%d\t",c[i][j]);

}

printf("\n");

}

}

How do you convert 9 grams in 15 centimeters?

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Asked by Wiki User

Grams measures mass. Centimeters measures length.

When can matrices be added or subtracted?

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Asked by Wiki User

When they have the same arrangement of numbers.

30-3 5+2 6-1 1+2 3-1 4+10

- Yes

6-0 9-4 1+2 2•2 10-7 5+8

2-1 4+2 1-3

- No

6-2 9+1 4+2

When do you call a pair of linear equation inconsistent?

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Asked by Wiki User

When there is no ordered n-tuple (pair, triplet, quartet - depending on the number of dimensions) that satisfies both equations at the same time. In graph form, it is when the straight lines representing the two equations are non-intersecting.

In 2 dimensions non-intersection implies that the lines are parallel.

What is x squared plus x -42?

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Asked by Wiki User

It is a quadratic expession and when factored is: (x-6)(x+7).

What is the system of equations?

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Asked by Wiki User

A system of equations is a set of equations with more than one variable dealing with the same material. If there are 2 variables, then the system must have 2 equations before it can be solved. 3 variables need 3 equations, etc.

Is y equals 23 linear?

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Asked by Wiki User

Yes.

If you were to plot y=23 on a graph, you'd have a straight horizontal line where y=23 (because no matter what the value of x is on the graph, y is always 23).

As the line that is plotted is straight, the equation is considered linear.

What is the answer to -9x72?

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Asked by Wiki User

-648

Which is greater a rate of change of 60 miles per hour or 1 mile per hour?

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Asked by Wiki User

A rate of change of 60 miles per hour.

Think of it in terms of a car. The car is going to go a father distance if it is going 60 miles per hour as opposed to 1 mile per hour.

How do you choose the appropriate conversion factors?

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Asked by Wiki User

Normally, you do not choose them: you calculate them.

What are the three different possible solutions of a linear system?

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Asked by Wiki User

If the lines cross then there is one solution. If they are on top of each other then there are infinite solutions. If they are parallel then there are no solutions.

How do you calculate percent by mass?

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Asked by Wiki User

Example:

- 454 g of orange jam contain 83 g sugar

454 g jam---------------83 g sugar
100 g jam----------------x g sugar

x= 100x83/454= 18,18 g sugar (or 18 % sugar)

How do you make math equations in word?

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Asked by Wiki User

you probably can, apart from the brackets and curvy x

Consider the subset of all 2x2 matrices where the determinant is 0 and trace of A transpose times A is 4 - is the set a manifold and if so what dimension manifold is it?

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Asked by Snetscm

Let M be the subset of 2x2 matrices A such that det(A)=0 and tr(A'A)=4 (I shall use ' to denote transpose).

Recall that one of the three definitions of a k-dimensional manifold is:

M c R^n is a k-dimensional manifold if for any p in M there is a neighborhood W c R^n of p and a smooth function F:W-->R^n-k so that F^-1(0) = M intersection W and rank(DF(x))=n-k for every x in M intersection W.

In short, what we need to do is find a function F so that the inverse image of the zero vector under F gives M and the rank of the derivative of F is equal to the dimension of the codomain of F.

Let an arbitrary 2x2 matrix be written as:

[a c]

[b d]

Then the two constraints that define M are

1) ad-bc=0

2) a^2+b^2+c^2+d^2=norm(a,b,c,d)^2=4

Define F:R^4-->R^2 by F(a, b, c, d)=(ad-bc, norm(a,b,c,d)^2-4). Then clearly F^-1(0,0)=M. Furthermore, F is smooth on M because the multiplication and addition of smooth functions (a, b, c, d) is also smooth. (Note that we have taken the neighborhood W to be some superset of M. This guaranteed to exist because if we interpret the set of 2x2 matrices as R^4, every point in M has norm 2, so any ball centered at the origin with length greater than 2 will contain M).

All that remains to be done is to check that rank(DF(x))=2 for every x in M. Observe that [DF]= [d -c -b a]

[2a 2b 2c 2d]

We shall now argue by contradiction. Suppose rank(DF) did not equal 2 for every x in M. Then we know that the two rows are linearly dependent i.e.

h[d -c -b a] + k[2a 2b 2c 2d] = 0 and h and k are not both 0.

Suppose h is 0. Then we have 2ka = 2kb = 2kc = 2kd = 0, and since k cannot also be 0, this implies that a=b=c=d=0, therefore norm(a,b,c,d)^2=0. But, (a,b,c,d) must be in M, so this is a contradiction. Hence h cannot be 0.

Now suppose h is nonzero. Then we can divide it out and there exists a, b, c, d and a constant k so that

[d -c -b a] + k[2a 2b 2c 2d] = 0 i.e. we have:

d + 2ka = -c + 2kb = -b + 2kc = a + 2kd = 0. From this we can substitute to obtain:

a(1 - 4k^2) = b(4k^2 - 1) = c(4k^2 - 1) = d(1 - 4k^2) = 0 and hence

a^2(1 - 4k^2)^2 = b^2(4k^2 - 1)^2 = c^2(4k^2 - 1)^2 = d^2(1 - 4k^2)^2 = 0.

Note that (1 - 4k^2)^2 = (4k^2 - 1)^2. Now, adding the four above expressions together we get:

(a^2 + b^2 + c^2 + d^2)(1 - 4k^2)^2 = norm(a,b,c,d)^2(1 - 4k^2)^2 = 0. But, since we require (a,b,c,d) to be in M, this reduces to 4(1 - 4k^2)^2 = 0. This implies that

1 - 4k^2 = 0, and hence k = +/-(1/2).

Now, if k=+1/2, then we have a + d = b - c = 0, therefore d = -a and b = c. Since we have det(A) = 0 as one of our constraints on M, this implies that ad - bc =

-(a^2) - (b^2) = -(a^2 + b^2) = 0, which implies a = b = 0, by the property of norms. But, if a = b = 0, then (a,b,c,d) = (0,0,0,0) and hence norm(a,b,c,d)^2 = 0, which is a contradiction.

We can argue analogously for the case where k = -1/2. Hence, assuming that rank(DF) is not 2 for some (a,b,c,d) in M leads to a contradiction, so we conclude that rank(DF)=2 for all x in M.

Finally, from this result, we conclude that since F:R^4-->R^2=R^(4-2), M must be a 2-dimensional manifold.

What would a 7x2 matrice and a 2x6 matrice form?

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Asked by Wiki User

A 7*2 matrix (not matrice) and a 2*6 matrix, if multiplied together, will from a 7*6 matrix.

What are the coordinates of the roots for 8x2 - 64x 120 0?

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Asked by Wiki User

If you mean: 8x2-64x+120 = 0 then x = 3 or x = 5

What are Complex vocal tics?

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Asked by GaleEncyofNeuroDis

Complex vocal tics involve meaningful words, phrases or sentences