[مازن سليمان]

4-3جتا2أ + جتا4أ
=3-4( 1-2(جاأ)2 ) + (2(جتا2أ)2-1)
=3-4(1-2(جاأ)2 ) + (2×(1-2(جاأ)2)2-1)
=3-4+8(جاأ)2+2+8(جاأ)4-8(جاأ)2-1
=8(جاأ)4