Simplify (3-5i)(3+5i)

$(3 - 5 i) (3 + 5 i)$

Step 1

Expand $(3 - 5 i) (3 + 5 i)$ using the FOIL Method.

Apply the distributive property.

$3 (3 + 5 i) - 5 i (3 + 5 i)$

Apply the distributive property.

$3 \cdot 3 + 3 (5 i) - 5 i (3 + 5 i)$

Apply the distributive property.

$3 \cdot 3 + 3 (5 i) - 5 i \cdot 3 - 5 i (5 i)$

Step 2

Simplify and combine like terms.

Simplify each term.

Multiply $3$ by $3$ .

$9 + 3 (5 i) - 5 i \cdot 3 - 5 i (5 i)$

Multiply $5$ by $3$ .

$9 + 15 i - 5 i \cdot 3 - 5 i (5 i)$

Multiply $3$ by $- 5$ .

$9 + 15 i - 15 i - 5 i (5 i)$

Multiply $- 5 i (5 i)$ .

Multiply $5$ by $- 5$ .

$9 + 15 i - 15 i - 25 i i$

Raise $i$ to the power of $1$ .

$9 + 15 i - 15 i - 25 (i^{1} i)$

Raise $i$ to the power of $1$ .

$9 + 15 i - 15 i - 25 (i^{1} i^{1})$

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$9 + 15 i - 15 i - 25 i^{1 + 1}$

Add $1$ and $1$ .

$9 + 15 i - 15 i - 25 i^{2}$

Rewrite $i^{2}$ as $- 1$ .

$9 + 15 i - 15 i - 25 \cdot - 1$

Multiply $- 25$ by $- 1$ .

$9 + 15 i - 15 i + 25$

Add $9$ and $25$ .

$34 + 15 i - 15 i$

Subtract $15 i$ from $15 i$ .

$34 + 0$

Add $34$ and $0$ .

$34$