# How to view complex number from quadratic equation ?

1. ## How to view complex number from quadratic equation ?

Hi

I have a query and was hoping someone could help me. I am trying to solve quadratic equations (148 to be exact) but some of the answers I get is "#NUM!"

I know this is because the answer is a complex number therefore cannot be displayed, but is there any way around this?

Here is an example:

A = 6.25
B = -38
C = 60

The answer is of a complex form, but how can I display this ?

Many thanks

Usman  Register To Reply

2. ## Re: How to view complex number from quadratic equation ?

You need to use the IM...() functions to perform the computations in the quadratic formula in order to perform the computations in complex space. IM...() functions are listed in the "engineering functions" : https://support.office.com/en-us/art...__toc309306710

For example, after computing the discriminant (b^2-4ac), you would use the IMSQRT(b^2-4*a*c) function to get the imaginary square root of the discriminant. You could then use the IMDIV() and IMSUM() functions to complete the quadratic formula.

Note that complex numbers are displayed as text strings (a+bi or a+bj, depending on your preference) in Excel to the numbers full precision (which means they tend to have a lot of digits displayed). If you want to separate the real and imaginary parts of the complex numbers so that you can round them to something reasonable, you can use the REAL() and IMAGINARY() functions to separate these out.

I discussed this briefly in this "math science and engineering" discussion group, including a sample spreadsheet: http://www.excelforum.com/groups/mat...lex-roots.html I don't know how well this forum's "groups" area works as far as storing and downloading spreadsheets. At one time, it seemed to work.  Register To Reply

3. ## Re: How to view complex number from quadratic equation ?

Thank you very much for your input.

For my first root, x1, I have the following equation:

=(-M8+IMSQRT((M8^2)-4*L8*N8))/(2*L8)

Where M8 is B, L8 is A and N8 is C. How would my equation look to represent what I am looking for ?

Thanks again.  Register To Reply

4. ## Re: How to view complex number from quadratic equation ?

You need to replace the + operation with the IMSUM() function, and the / operation with the IMDIV() function. So, for example, the numerator might be =IMSUM(-M8,IMSQRT(M8^2-4*L8*N8)).  Register To Reply