How do you invert a 2x2 matrix?

Take a matrix A=(acbd), where a,b,c,d are numbers.

First find the determinant. This is ad-bc.

Now, rearrange the matrix to become (d-c-ba). Divide this by the determinant, to have A-1=1/(ad-bc)(d-c-ba). This is the inverse of A.

YP

Related Further Mathematics A Level answers

All answers ▸

Find the reflection of point P(2,4,-6) in the plane x-2y+z=6


Prove by induction that (n^3)-n is divisible by 3 for all integers n>0 (typical fp1 problem)


Express cos5x in terms of increasing powers of cosx


Find the stationary points of the function z = 3x(x+y)3 - x3 + 24x