Unit 4, Lesson 13
Multiplying Complex Numbers
Algebra 2
Practice
Problem 1
Which expression is equivalent to \(2i(5+3i)\)?
\(\text-6 + 10i\)
\(6 + 10i\)
\(\text-10 + 6i\)
\(10+ 6i\)
Problem 2
Lin says, “When you add or multiply two complex numbers, you will always get an answer you can write in \(a + bi\) form.”
Noah says, “I don’t think so. Here are some exceptions I found:”
\((7 + 2i) + (3 - 2i) = 10\)
\((2 + 2i)(2 + 2i) = 8i\)
- Check Noah’s arithmetic. Is it correct?
- Can Noah’s answers be written in the form \(a+bi\), where \(a\) and \(b\) are real numbers? Explain or show your reasoning.