Tapping into mathematics
Tapping into mathematics

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

Tapping into mathematics

7.3 Square rooting a negative number

Another problem surfaces if you start with a negative number and try to find its square root. For example try to find the square root of 4 on your calculator. Depending upon how your calculator is set up, you may either get an error message or an unfamiliar number like 2i or 2j. This is because there is no real number which squared will give you the negative number 4. Every real number, whether positive or negative, has a positive square. There are some numbers, called imaginary numbers, which are the square roots of negative numbers and they do have uses in mathematics. You may come across them in more advanced mathematics and some scientific and graphics calculators will allow you to calculate with them. However in general you are likely to get an error message if you try to square root a negative number. So square roots must be handled with care.

Figure 8
Figure 8 Finding the square root of a negative number gives an error message
MU120_4MCAL

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371