(a^2+b^2)(a^2+b^2-1)-56=0,a^2+b^2=?若x^2-3x+1=0,则x^4-7x^2+1be quickly!

(a^2+b^2)(a^2+b^2-1)-56=0,a^2+b^2=?若x^2-3x+1=0,则x^4-7x^2+1be quickly!
(a^2+b^2)(a^2+b^2-1)-56=0,a^2+b^2=?
若x^2-3x+1=0,则x^4-7x^2+1
be quickly!

(a^2+b^2)(a^2+b^2-1)-56=0,a^2+b^2=?若x^2-3x+1=0,则x^4-7x^2+1be quickly!
a^2+b^2=-7或8
设a^2+b^2=x,代入,即为x^2-x-56=0,用十字相乘法解出x,即为
a^2+b^2=
第二问,x^4-7x^2+1=0
由题得,x^2=3x-1,代入x^4-7x^2+1中,得9(x^2-3x+1)
即x^4-7x^2+1=0