In a pair of coils, with L₁ = 0.1 H and L₂ = 0.2 H, at a certain moment, i₁ = 4 A and i₂ = 10 A. Find the total energy in the coils if the coupling coefficient M is

(a) 0.1 H,

(b) √2 /10 H,

(c) -0.1 H, and 

(d) - √2 /10 H.