Question

已知集合{x|x²+px-2=0},且1∈A,求p的值及集合A

Answer 1

A= {x|x²+px-2=0}, and 1∈A,
then
1+p-2=0
p=1#

and when p=1,
x²+x-2=0
(x+2)(x-1)=0
x= 1 or -2
A={1,-2}

Answer 2

x=1 代入x²+px-2=0得 p=1

x^2+x-2=0解得x=1或x=-2

A={1,-2}