help with matrix

[raven2k7]

It says * knowing that the matrix is equal to =10 (i would like to know how they know that) calculate the determinate for the matrix below *

the file is attached. any help would be appreciated , thank u

 

[Cubist]

Sometimes a question can be phrased like this:-

Given that x=5 calculate the value of x+2

The answer is obviously 7. Don't waste your time trying to work out why x is 5 in the first place

In this question they are asking you to manipulate the determinant of 2nd matrix to look like the given determinant. See this wiki page(click) for how this can be done. For example point 14 under the section "Properties of the determinant" reads, "Adding a scalar multiple of one column to another column does not change the value of the determinant"

 

[Steven G]

They don't know that the determinant (NOT matrix) = 10. They mean assuming the determinant = 10 solve the problem.

 

[raven2k7]

yes you are right i realized that afterwards. thanks so much