Simplify (7- square root of -1)- square root of -81

$(7 - \sqrt{- 1}) - \sqrt{- 81}$

Simplify each term.

Rewrite $\sqrt{- 1}$ as $i$ .

$7 - i - \sqrt{- 81}$

Rewrite $- 81$ as $- 1 (81)$ .

$7 - i - \sqrt{- 1 (81)}$

Rewrite $\sqrt{- 1 (81)}$ as $\sqrt{- 1} \cdot \sqrt{81}$ .

$7 - i - (\sqrt{- 1} \cdot \sqrt{81})$

Rewrite $\sqrt{- 1}$ as $i$ .

$7 - i - (i \cdot \sqrt{81})$

Rewrite $81$ as $9^{2}$ .

$7 - i - (i \cdot \sqrt{9^{2}})$

Pull terms out from under the radical, assuming positive real numbers.

$7 - i - (i \cdot 9)$

Move $9$ to the left of $i$ .

$7 - i - (9 \cdot i)$

Multiply $9$ by $- 1$ .

$7 - i - 9 i$

Subtract $9 i$ from $- i$ .

$7 - 10 i$