A student multiplies (4+5i) (3-2i) incorrectly and obtains 12-10i what is the students mistakes

1. In the multiplication of the imaginary parts, the student forgot to square of i. OR

2. The student has only multiplied the real parts and the imaginary parts.

Correct value .

Step-by-step explanation:

The given expression is

A student multiplies (4+5i) (3-2i) incorrectly and obtains 12-10i.

Student's mistake can be either 1 or second:

1. In the multiplication of the imaginary parts, the student forgot to square of i.

2. The student has only multiplied the real parts and the imaginary parts.

Which is not correct. The correct steps are shown below.

Using distributive property, we get

Therefore, the correct value of is .

See below

Step-by-step explanation:

I will assume the given denominator is 3a as there is nothing attached to the statement.

Lets first look at the domain of 2a+b. As it is a polynomial with unknowns a and b, we know it has its domain in all real numbers for both  a and b as every polynomial does. For verifying it replace a and b by any real number you can think of.

Domain = a, b belonging to R

Now, if we divide 2a+b by 3a we will have:

(2a+b)/3a

As know we don not have a polynomial we cant state that the domain will still be all the real numbers for sure. We need to go further.

We have a fraction and as every fraction the denominator CAN'T be equal to 0, so 3a MUST be different to 0. This means that a MUST be different to 0. So, now our domain changes:

domain' = a, b belonging to R and a different to 0.