Question

Multiply (5 + 3i)(5 − 3i) 16 + 15i 16 − 15i 16 34

Answer 1

Answer:

34

Step-by-step explanation:

Answer 2

Answer:

(5 + 3i)(5 − 3i) = 34

Step-by-step explanation:

The multiplication of two identical binomials who have different symbol, can be solved using the factoring case of a difference of squares:

$(a-b).(a+b)=a^{2}-b^{2}$

So, in this case:

$(5+3i).(5-3i) = 5^{2}-(3i)^{2}$

$=25-9i^{2}$

Remember that $i=\sqrt{-1}$

So: $i^{2}=-1$

We replace on the polynomial:

$=25-9.(-1) = 25+9=34$