Questions on Algebra: Matrices, determinant, Cramer rule answered by real tutors!

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Question 166212: Can someone help with this problem please:
Solve the matrix equation for X.
A =
2 0 0
-1 2 0
-2 4 1

B =
4
10
11
AX = B
CHOOSE FROM:
a.
0
8
-9

b.
2
6
-9

c.
3
7
-8

d.
3
6
-10: Can someone help with this problem please:
Solve the matrix equation for X.
A =
2 0 0
-1 2 0
-2 4 1

B =
4
10
11
AX = B
CHOOSE FROM:
a.
0
8
-9

b.
2
6
-9

c.
3
7
-8

d.
3
6
-10
Answer by Fombitz(1789) About Me  (Show Source):
You can put this solution on YOUR website!
AX=B
X=A^(-1)B
Find the inverse of A.
A=(matrix(3,3,<BR> 2 ,0 ,0<BR> ,-1, 2, 0,<BR> -2, 4, 1 ))
A^(-1)=(1/4)*(matrix(3,3,<BR> 2 ,0 ,0<BR> ,1, 2, 0,<BR> 0, -8,4 ))

Multiply rows of the inverse matrix by the column matrix to get the product.
X[1]= (1/4)*(2(4)+0(10)+0(11))=2
X[2]= (1/4)*(1(4)+2(10)+0(11))=6
X[3]= (1/4)*(0(4)+(-8)(10)+4(11))=-9
.
.
.
(matrix(3,3,<BR> 2 ,0 ,0<BR> ,-1, 2, 0,<BR> -2, 4, 1 ))*(matrix(3,1, <BR> 2,6,-9 ))=(matrix(3,1, <BR> 4,10,11 ))
.
.
.
b.)
X=(matrix(3,1, <BR> 2,6,-9 ))