Answer:
The value of a is -6.
Step-by-step explanation:
A complex number is defined as
where, x is real part and iy is imaginary part.
The given equation is
Here real part is a and imaginary part is -i. So, x=a and y=-1.
Taking square on both the sides.
Subtract 1 from both the sides.
Taking square root on both the sides.
The value of a is either 6 or -6. But it is given that the picture is in third quadrant, so the value of a can not be positive.
Therefore the value of a is -6.