%EX3

% q1
A=[6 43 2 11 87 ; 12 6 34 0 5; 34 18 7 41 9]

VA=A(2,:)

VB=A(:,3)
VB=VB'
% or VB=A(:,3)'

VC=A([1 2] , :)
VC=VC(:)
VC=VC'
% or VC1=[A(1  , :)   A(2 ,:)]
% or  VC=VC'   VC=VC(:)'
% using reshape : reshape(VC, 1, numel(VC))   or reshape(VC', 1, numel(VC))

VD=A(:,[2 5 ])
VD=VD(:)
VD=VD'
% using reshape:  reshape(VC,  numel(VC), 1)

%q2
c=[2:2:10 ; 3:3:15; 7:7:35]

UA=c(:,3)

UB=c(2,:)'

UC=c(:,1:2:5)  
% or UC=c(:,[1 3 5]) 
UC(:)
% or UC=[c(:,1) ; c(:, 3); c(:, 5)] 

UD=c(1:2,:)'
UD(:)

%q3
A1 = ones(3);
A2 = zeros(3,2);
A4 = ones(2)*5;
A = [ A1 A2 ; A2' A4]
% or  A1 = ones(3);  A1(4:5,4:5)=5