Question

Re(5+7i)=
a)7
b)5
c)12
d)7i​

Answer 1

Let z = 5 + 7i

We have to find the Real part of complex number Re(5+7i).

Solution:

We know that,

Definition of complex number,

z = x + iy

Where, x is called real part of z and  

y is called imaginary part of z

∴ z = 5 + 7i

Here, real part of z = 5

Thus, the value of Re(5 + 7i) is "equal to b)5".

Answer 2

Given:

Given complex number is: $5 + 7i$

To find:

We need to find the real part of given complex number.

Solution:

Let the given complex number is $z=5 + 7i$.

Generally, a complex number contains 2 parts, i.e., real part and imaginary part.

Example: $z = x + iy$

Here, $x$ is called as real part and $y$ is called imaginary part.

Now compare the given number with above number.

5 is the real part and 7 will be the imaginary part.

So, the real part of given complex number is 5.

Therefore, option b is correct.