Question

若a的平方加a减3等于0，则a的4次方加2a的3次减a减1等于几？

要具体过程！

Answer 1

a^2+a-3=0
a^4+2a^3-a-1=?
是这个意思？
a^4+2a^3-a-1=[(a^2+a)^2]-[a^2+a]-1=[a^4+2a^3+a^2]-[a^2+a]-1=9-3-1=5

Answer 2

a^2+a-3=0
a^2+a=3

a^4+2a^3-a-1
=a^2(a^2+a)+a^3-a-1
=3a^2+a^3-a-1
=a(a^2+a)+2a^2-a-1
=3a+2a^2-a-1
=2a^2+2a-1
=2(a^2+a)-1
=6-1
=5

Answer 3

a+1=3/a
a4+a3+a3-a-1=a3*3/a+a3-a-1
=3a2+a3-a-1
=a2*3/a+2a2-a-1
=2a*3/a-1
=5

Answer 4

a^2+a-3=0
a^2=3-a
a^4+2a^3-a-1
=(3-a)^2+2a(3-a)-a-1
=a^2-6a+9+6a-2a^2-a+1
=-a^2-a+10
=a-3-a+10
=7