If neither a nor b are equal to zero, which answer most accurately describes the product of (a + bi)(a - bi)?

the imaginary part is zero.
the real part is zero.
the imaginary part is positive.
the real part is not positive.

The imaginary part is zero.

Step-by-step explanation:

we know that

Applying the difference of squares formula  

Remember that

substitute

therefore

The imaginary part is zero.

step-by-step explanation:

try remembering the steps

there is no question content here, but you for the free points! : d