Răspuns:
Salut
a=x+1/x
a²=x²+1/x²+2x/x
a²=x²+1/x²+2
a⁴=(x²+1/x²+2)²=
x⁴+1/x⁴+4+2x²/x²+2x²*2+2*2/x²
x⁴+1/x⁴+4+2+4x²+4/x²=x⁴+1/x⁴+6+4x²+4/x²
a⁴=x⁴+1/x⁴+6+2-2+4x²+4/x²
a⁴=x⁴+1/x⁴+4x²+4/x²+8-2
a⁴=x⁴+1/x⁴+4(x²+1/x²+2)-2
a⁴=x⁴+1/x⁴+4a²-2
x⁴+1/x⁴=a⁴-4a²+2
Explicație pas cu pas:
