Which values of x and y would make the following expression represent a real number? (4+5i)(x+yi)

So x=4 and y=-5 would work.

Step-by-step explanation:

When you multiply complex conjugates, you get a real result.

Example:

I replace with -1 since .

is a real number (there is no imaginary part, no i).

So what is the conjugate of 4+5i?

4-5i

So x=4 and y=-5 would work.

A multiple of the complex conjugate would work as well.

This is still a real number; there is no imaginary part,no i.

the answer will be