How to find inverse of a 4x4 Matrix?
matrix
(a b
c d)
Inverse
1/┃A┃ x ( d -b
-c a)
In unconstrained optimisation, how can we prove a maximum?
fxx(x,y)≤0 (concave)
┃H(x,y)┃>=0
In unconstrained optimisation, how can we prove a minimum?
fxx(x,y)>=0 (convex)
┃H(x,y)┃>=0
When does a saddle point occur?
┃H(x,y)┃<0
What occurs when it could be max, min or neither
┃H(x,y)┃=0
How do you find inverse of a 3x3 matrix?
Make (A┃I)
Put matrix in augmented form next to another 3x3 matrix of just 1s going down. use row methods to move 1s ot left hand side.
How to find the coefficient of variation
standard deviation over mean. x100
How to find correlation coefficient
Covariance/
(sdx x sdy)
How to find number of permutations?
n! / (n-k)!
n-k is how many left over
How to find the number combinations of k objects chosen from n?
n! / k! (n-k)!
