Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫  π  -¹ ² ³ °

You are not logged in.

## #1 2006-08-21 22:04:02

zegoat
Member
Registered: 2006-08-21
Posts: 7

### Engineering Mathematics Questions Help - - -complex Numbers

Hi

QUESTION 1

A
Can anyone answer these questions? And show working out...

If
A = (2  -1  0       ,  B = (3      ,      C = (1  6  5
-1   1  6)                 2                    3   4  1)
4)

Find, where possible: 3A-B, AB and CA

B

Let
E= (2  5     and   F = (4  -5
-3  1)                   3   k)

For what values of k, if any, does EF=FE

Find the inverse of E and hence solve:

2x + 5y = -4
-3x + y = 7

C

Let M =  (0  1  2
1  0  3
4 -3  8)

Find the determinant and inverse of M

hence solve the system:

y + 2z = -11
x + 3z = -20
4y - 3y + 8z = -61

Offline

## #2 2006-08-22 03:30:29

stacey
Member
Registered: 2006-08-21
Posts: 8

Offline

## #3 2006-08-22 05:18:57

luca-deltodesco
Member
Registered: 2006-05-05
Posts: 1,470

### Re: Engineering Mathematics Questions Help - - -complex Numbers

is addition and subtraction allowed for matrices with different dimensions? i dont think so

CA is not allowed, the number of collumns of C is not equal to the number of rows in A, so multiplication doesnt work

B)

the rest i dont know

The Beginning Of All Things To End.
The End Of All Things To Come.

Offline

## #4 2006-08-22 06:18:32

numen
Member
Registered: 2006-05-03
Posts: 115

### Re: Engineering Mathematics Questions Help - - -complex Numbers

C)

Maybe I'll do the inverse later, god I'm hungry But basically, MX=Y, so the inverse is what you'll find in front of Y in X=M-¹Y.

Bang postponed. Not big enough. Reboot.

Offline

## #5 2006-08-22 22:28:07

stacey
Member
Registered: 2006-08-21
Posts: 8

### Re: Engineering Mathematics Questions Help - - -complex Numbers

can no one answer these questions?

Offline

## #6 2006-08-22 22:29:07

stacey
Member
Registered: 2006-08-21
Posts: 8

### Re: Engineering Mathematics Questions Help - - -complex Numbers

sorry i meant on my post lol

Offline