1. ## [SOLVED] Matrices prob

I can find p=1 and q=-2 but I don't know how to deduce M^4 = -5M + 6I??

Thanks.

2. Originally Posted by stpmmaths

I can find p=1 and q=-2 but I don't know how to deduce M^4 = -5M + 6I??

Thanks.
HI

using the results you got above , assuming its correct .

$\displaystyle m^2=-m+2I$

$\displaystyle m^3=-m^2+2mI$

$\displaystyle =-(-m+2I)+2m$

$\displaystyle =3m-2I$

$\displaystyle m^4=3m^2-2mI$

$\displaystyle =3(-m+2I)-2m$

$\displaystyle =-5m+6I$

3. Sorry, I can't get it. Matrices follow distributive law??

4. Originally Posted by stpmmaths
Sorry, I can't get it. Matrices follow distributive law??
You need to be much more specific. What don't you get? Which line in virtually the complete solution that's been given to you do you not understand?

5. Matrices follow distributive law? Meaning a(b+c)=ab+bc.

6. Originally Posted by stpmmaths
Matrices follow distributive law? Meaning a(b+c)=ab+bc.
Yes (assuming the multiplication a(b+c) is valid).

7. Thanks for all the effort.