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December 21st, 2010, 11:26 PM  #1 
Senior Member Joined: Dec 2010 Posts: 233 Thanks: 0  Matrix question (confusing)
Given that A=( ) a11=2, a12=2, a21=3, a22=1, (it is a matrix, sorry I can't type matrix in word) find A^2 and A^3. If f(x)= x^33x^22x+4, find f(A). If g(x)=x^2x8, find g(A). I have solved many kinds of problem in matrix, but this confusing me a lot. I dunno how to do. I only can find A^2 and A^3. Please help me step by step. 
December 22nd, 2010, 05:25 AM  #2 
Senior Member Joined: Dec 2010 Posts: 233 Thanks: 0  Re: Matrix question (confusing)
help me !!!

December 22nd, 2010, 07:40 AM  #3 
Global Moderator Joined: Dec 2006 Posts: 19,882 Thanks: 1835  To add matrices (of the same size), add corresponding elements. To multiply a matrix by a constant, multiply each element of the matrix by the constant. I suggest interpreting "+ 4" and " 8" as "+ 4I" and " 8I", where I is the identity matrix (having 1 as each element of the main diagonal, and zero for all the other elements). Hence g(A) = A²  A  8I = Can you complete the answer by finding f(A) now? 
December 23rd, 2010, 06:58 AM  #4 
Senior Member Joined: Dec 2010 Posts: 233 Thanks: 0  Re: Matrix question (confusing)
I don't really understand. Anyone else can help?

December 23rd, 2010, 09:01 AM  #5 
Global Moderator Joined: Dec 2006 Posts: 19,882 Thanks: 1835 
Can you be more specific? For example, do you know how matrix multiplication is done?

December 30th, 2010, 09:28 PM  #6 
Newbie Joined: Dec 2010 From: india Posts: 1 Thanks: 0  Re: Matrix question (confusing)
Hi, Dear hoyy1kolko, I understand your problem. I suggest this site for your problems. This is an easy calculation site for all math problems. 

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