if i = square root of -1 what is the sum (7 + 3i) + (-8 + 9i)

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if i = square root of -1 what is the sum (7 + 3i) + (-8 + 9i)

We group like terms, and we get:
7 - 8 + (3 + 9)i

Simplifying, we get:
-1 + 12i