# Math

posted by .

find the values of a and b given that matrix A=
[a -4 -6]
[-8 5 7]
[-5 3 4]
is the inverse of matrix B =
[1 2 -2]
[3 b 1]
[-1 1 -3]
It would really help if you showed how you did it.
Thanks a lot!

• Math -

I trust you know how to multiply two matrices

and I trust that you know that if you multiply any matrix by its inverse you get the identity matrix, namely
1 0 0
0 1 0
0 0 1

so using the first row of matrix A and the first column of matrix B you get
a - 12 + 6 = 1
a = 7

then second row of A by second column of B gives us
-16 + 5b + 7 = 1
b = 2

## Similar Questions

1. ### Math

Let A, B, and 0 be 2x2 matrices. Assuming that A is invertible, find a matrix C such that [A^-1|0 ] [C |A^-1] is the inverse of the partitioned matrix [A|0] [B|A]
2. ### math,algebra II

I have to work with these types of problems dealing with matrises can someone show me how to solve them.Heres one of them: Directions: Find the values of the variables in each equation in the first matrix it looks like this a+2 3z+1 …
3. ### algebra

When i have a matrix 4 X 4 and i have to multiply it by a 4 X 3 i know that the product size has to be a 4x 3 so do i do a row times column or how ?
4. ### Algebra II (Matrices)

My book doesn't solve it like a linear equation, they solve it by using inverse matrices. Solve the matrix equation: |4 -5||m|=|32| |1 2| |n|=|-5| A= |4 -5| |1 2| X= |m| |n| B= |32| |-5| Step 1. Find the inverse of the coefficient …
5. ### MATHS----Matrix

For a given square matrix A the predicted values of matrix B are: predicted B=A(A'A)^(-1)A'B why is the matrix C=A(A'A)^(-1)A' an idempotent and symmetric matrix?
6. ### Math

Fine the size of the following matrix and its additive inverse matrix. Identify if it is a square, column, or row matrix: [ 2 -3 7 1 0 4 ]
7. ### math

This is a matrix question. R is the matrix (3r 1) (s 2s) 1. State, in terms of s and r the determinant of R 2. If r=1/3 and s=4 determine the inverse of R 3.State the pair of r and s not including 0, which would make the matrix R a …
8. ### math

This is a matrix question. R is the matrix (3r 1) (s 2s) 1. State, in terms of s and r the determinant of R 2. If r=1/3 and s=4 determine the inverse of R 3.State the pair of r and s not including 0, which would make the matrix R a …
9. ### Calc

A video games shop is analyzing its sales performance using matrices. Matrix A contains the unit sales data for each product category (horizontally) per week (vertically). Matrix B contains the unit sales data for weekends for each …
10. ### Math

Hi! I need help with these two questions. Thanks! :) 1.) Can we multiply the Matrix A (which is 3 x 4 matrix) by the other matrix, Matrix B (which is 3 x 4 matrix)?

More Similar Questions