Răspuns:
Explicație pas cu pas:
a = 1/√3 x ( 1/2 + 1/3 ) : 1/√3 ×[( 2+3√3)/3 - (√3-1)]
1/√3 : 1/√3 = 1/√3 × ( √3/1) = 1
a = ( 3/6 + 2/6 ) : [ ( 2+3√3)/3 - 3(√3-1)/3]
a = (5/6) : [ (2+3√3-3√3+3)/3]
a = (5/6) : ( 5/3)
a = (5/6)×(3/5)
a = 1/2
a ⁻¹ = ( 1/2)⁻¹ = 1 /(1/2) = 1 x 2/1 = 2 ∈ N