Higher order roots
In this article, we will expand the concepts of square roots and cube roots to roots of any order.
If you don't know what square and cube roots are, we recommend that you check out this lesson.
Quick review of square and cube roots
To find the square root of a number , we look for a number whose square is . For example, since , we say that the square root of , written as , is .
Similarly, to find the cube root of a number , we look for a number whose cube is . For example, since , we say that the cube root of , written as , is .
Let's continue that pattern! To find the root of a number , we look for a number which, raised to the power, equals . For example, since , we say that the root of , written as , is .
Let's practice finding some roots
And our journey continues! To find the root of a number , we look for a number which, raised to the power, equals . For example, since , we say that the root of , written as , is .
Let's practice finding some roots
Other higher order roots
We can continue this way and define roots, roots etc. For example, , so the root of , written as , is .
Let's do some more problems with higher order roots
Want to join the conversation?
- it doesn't show you how to solve for a fraction.(31 votes)
- for a fraction, you just find the roots for both the denominator and the numerator. For example, if you are finding the 4th root of 16/243, you find the 4th root of 16(which is 2) and the 4th root of 243(which is 3) so the answer would be 2/3.
Hope that helped(68 votes)
- What are imaginary numbers(23 votes)
- It's a complex number that is written as i, which means the square root of -1, which is impossible.(37 votes)
- I'm not getting this at all i need help(20 votes)
- Try to [truly] understand what Sal is doing in this video: https://www.khanacademy.org/math/algebra/x2f8bb11595b61c86:rational-exponents-radicals/x2f8bb11595b61c86:radicals/v/5th-roots(9 votes)
- um so how come when i take a unit test its always something else instead of what i was taught...(15 votes)
- i honestly think so to... but khan is trying to give you a challenge to expand your mind and DIY! thats why they make the tests harder!(20 votes)
- How do you find a decimal root.(9 votes)
- Do you mean the square root of a decimal such as √.64?(15 votes)
- im a bit confused about the 9th root.(7 votes)
- So basically they phrased the question in a tricky way. When they say: "Pick the correct equality that describes 2 as the ninth root of a number." You need to remember that the any root, whether higher order, cube, or square, is the inverse of its counterpart: exponents. So essentially the real question they are asking you is: 2 to the power 9. All you need to do is solve for this and your answer will coincide with one of the multiple choice.(13 votes)
- So tough but finally figured it out(10 votes)
- Congratulations. Is this school required for you? If so, I feel your pain.😬(7 votes)
- I wish we could add screenshots so we could get help with problems that are not on Khan.(11 votes)
- If we can do square roots to cube roots to 5th roots to 7th roots then can we do 8th root, 9th root and 10th root etc?(6 votes)
- Yep,any rational number can be a root and easily depicted(7 votes)
- Is there a easier way to find a higher roots answer(8 votes)
- Other than using a calculator, I don't think so.(0 votes)