Discrete Math
posted by Ryan .
I am really stuck on these problems. I've worked a lot of them but I can't get these. Sometimes I
think I know the answer but I can't show how I got it.
1.) Solve each matrix equation for X.
2X + 5A = B
2.) Find the following matrices: a. AB b. BA
A=
2 4
3 1
4 2
B=
3 2 0
1 3 5
3.) Find A1 by forming AI and then using row operations to obtain IB, where A1 = B, check that
AA1=I and A1 A = I
A=
2 4 4
1 3 4
2 4 3
4.) Write the system of linear equations represented by the augmented matrix. Use x,y,z and, if
necessary w,x,y and z for the variables.
7 0 43
0 1 511
2 7 06
5.) Use Gaussian elimination to find the complete solution to each system of equations, or show that
none exist.
3w + 2x  y + 2z = 12
4w – x + y + 2z = 1
w + x + y + z = 2
2w + 3x + 2y – 3z = 10
6.) Use Cramer’s rule to solve the system
X – 3y + z = 2
x + 2y = 8
2x – y = 1
7.) Use Cramer’s rule to solve the system
2x + 2y + 3z =10
4x – y + z = 5
5x 2y + 6z = 1
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