Question 205677
1). 
81^2-y^2
= (9-y)(9+y)
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3).
100x^2y^2-121
= (10xy-11)(10xy+11)
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5).
49x^2z^2-100y^2
= (7xz-10y)(7xz+10y)
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7).
8x^#+125
= ?
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9).
64x^3+1
= (4x^3)+1
= (4x+1)((4x)^2 - 4x + 1)
= (4x+1)(16x^2 - 4x + 1)
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Cheers,
Stan H.