Question

1. write $sqrt{81}+sqrt{-36}$ in the form $a + bi$.

9 - 6i
6i - 9
9 + 6i
-6i + 9

Explanation:

Step1: Calculate square - root of 81

$\sqrt{81}=9$

Step2: Calculate square - root of - 36

$\sqrt{-36}=\sqrt{36\times(-1)}=\sqrt{36}\times\sqrt{-1}=6i$ (since $i = \sqrt{-1}$)

Step3: Combine the results

$\sqrt{81}+\sqrt{-36}=9 + 6i$

Answer:

C. $9 + 6i$