The pencil work in your workbook is correct, EXCEPT for the very last number ...
The last number is (4 x 3). That's '12', not '7'.
The answer is z²+7z+12 Just use FOIL.
To simplify ( z + 4 ) ( z + 3 ) , use the distributive property or FOIL method to get z 2 + 7 z + 12 . You multiply the first, outer, inner, and last terms, then combine like terms. The final result is a quadratic expression.
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