So m is not equal to 0.

Divide both sides of the equation by m at the same time

M-5- 1/m=0。

m- 1/m=5

Both sides are squares.

m^2-2+ 1/m^2=25

m^2+ 1/m^2=27

The original formula is equal to = m2+1/m2+m2-5m = 27+1= 28.