Simplify each of the products: `(x^2+x-2)(x^2-x+2)`

Explanation

we can write it as,
`[x^2+(x-2)][x^2-(x-2)]`
this is the form of `(a+b)(a-b)=a^2-b^2`
so
`[x^2+(x-2)][x^2-(x-2)]`
`=x^4-(x-2)^2`
`=x^4-(x^2-4x+4)`
`=x^4-x^2+4x-4`