Thread: [SOLVED] some matrices help

hi, some more matrices problems that i can't solve
no 1 :

a) Find PQ which i did =

i can't solve b which is

b) Find a matrix X such that PX + Q = P




no2) If work out and

hence show that

i worked out x^2 and X^3 , and i tried doing the above calculations but didn't get x^3
what should i do?

thanks in advance

For #1b you must first find .
Then .

#2 is just a matter of doing all the caculations correctly.

Originally Posted by llkkjj24

no2) If work out and

hence show that

i worked out x^2 and X^3 , and i tried doing the above calculations but didn't get x^3
what should i do?

thanks in advance

Hi llkkjj24,

As Plato points out, you need to know the inverse of P to solve the first part. Did you notice what the value of PQ is? If so, what is Q?

thanks, i noticed for no1 i did a mistake, i multiplied x^2 with x^2 instead of multiplying it with X to get x^3

Originally Posted by qmech

As Plato points out, you need to know the inverse of P to solve the first part. Did you notice what the value of PQ is? If so, what is Q?

yes, Q is the inverse of P

thanks guys, problem solved