Try another version of this question Factor `9x^-4-4` `(` `x^-2+` `)(` `x^-2-` `)` `9x^-4-4 = ( 3 x^-2+ 2 )( 3 x^-2- 2 )`
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`(` `x^-2+` `)(` `x^-2-` `)`