Question

(ab - 9)(ab + 8) Please help

Answer 1

Use FOIL. :)

(ab - 9)(ab + 8)
ab^2 + 8ab - 9ab + 72
Simplify: 
ab^2 - ab - 72

Answer 2

a^2 b^2 + 8ab - 9ab - 72
a^2 b^2 + (8ab - 9ab) - 72
$a^{2}$ $b^{2}$ - ab - 72

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