Radical Operations

Concept sheet | Mathematics

Adding Irrational Numbers

Case 1: Adding Two Radicals With Different Radicands

To be as accurate as possible, we have to leave the operation as is. It is not possible to simplify it further.
It is possible to transform irrational numbers into decimals and add them together. However, we will have to use rounding, which will make the answer less precise.

Example

|\sqrt{5}+\sqrt{3}|  

|\sqrt{5}+\sqrt{3}\approx2.2361+1.7321\approx3.9682|

Case 2: Adding Two Radicals With Identical Radicands

The radicands can be grouped for an exact answer or transformed into decimal numbers.

Example

|\sqrt{3}+\sqrt{3}=2\sqrt{3}|

or

|\sqrt{3}+\sqrt{3}\approx1.7321+1.7321\approx3.4642|

Case 3: Adding Two Irrational Numbers

Whether it is a fraction consisting of the number pi or a radical accompanied by another term, it is necessary to put everything in decimals and then proceed to the addition.

Example

|\sqrt{2}+\pi\approx1.4142+3.1416\approx4.5558|

Subtracting Irrational Numbers

When subtracting, we use the same principles as with adding.

Example

|\sqrt{5}-\sqrt{3}\approx2.2361-1.7321\approx0.5040|

|2\sqrt{3}-\sqrt{3}=\sqrt{3}|
or
|2\sqrt{3}-\sqrt{3}\approx3.4641-1.7321\approx1.7321|

|\pi-\sqrt{2}\approx3.1416-1.4142\approx1.7274|

Multiplying Irrational Numbers

When multiplying a square root with an identical one, the answer is the value of the radicand.

Example

|\sqrt{3}\cdot\sqrt{3}=3| 

If the radicals are different, it suffices to recreate an expression where the two radicands multiply together under the same root.

Example

|\sqrt{5}\cdot\sqrt{3}=\sqrt{15}|

Dividing Irrational Numbers

When the radical is the same in the numerator and in the denominator, it suffices to reduce them together.

|\frac{\sqrt{2}}{\sqrt{2}}=1|

|\frac{4\sqrt{3}}{2\sqrt{3}}=2|

If the radicals are different, it suffices to create a new fractional expression where the two radicands are found under the same root.

Example

|\frac{\sqrt{12}}{\sqrt{3}}=\sqrt{\frac{12}{3}}=\sqrt{4}=2|

|\frac{2\sqrt{6}}{\sqrt{2}}=2\sqrt{\frac{6}{2}}=2\sqrt{3}|