Question 330071
7x^2y - 6 - 4xy^2 + 9x^2y - 9 
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group the similar terms
7x^2 y +9x^2 y -4xy^2-6
16x^2y-4xy^2-6
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16x^2y 16 co-efficient and variable x^2y
-4xy^2 -4 co-efficient and variable xy^2
constant = -6