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

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

 the correct option is

(D) The imaginary part is zero.

Step-by-step explanation:  Given that neither a nor b are  equal to zero.

We are to select the correct statement that accurately describes the following product :

We will be using the following formula :

From product (i), we get

So, there is no imaginary part in the given product.

Thus, the correct option is

(D) The imaginary part is zero.

c.   x=2.4cm

step-by-step explanation:

similar triangles are triangles which have the same shape but not the same size. this means their angle measures are equal but their side lengths are not instead they are proportional. to solve, we will set up a proportion and solve.

a proportion is two equal ratios set equal to each other. we form the ratios by finding corresponding sides (sides which match to each other on both triangles by their position). out ratios will be one side of the small triangle over the corresponding side on the big triangle as shown below:

.

to solve the proportion, we'll cross multiply by multiplying numerator with denominator across the equal sign.