Definition
Radical symbol
The radical symbol √ is the notation that tells you to find a root.
Continue from this idea into connected AXIO math.
Defining relationship
The radical symbol is a root roof: it covers exactly what belongs inside the root.
The radical symbol √ marks a root. With no written index it denotes the principal square root; a small index, such as 3 in ∛, names another root.
- 1
radical roof covers the radicand 9
- 2
check the root
- 3
a written index names another root
- No index means principal square root
- The roof scope shows what is inside
What it means
The symbol has a check-shaped start and a bar that covers the number or expression being rooted. Look for a small index: no index means square root, while 3 means cube root.
Remember it
The radical symbol is a root roof: it covers exactly what belongs inside the root.
Example
In ∛125, the radical symbol includes a small index 3, so it asks for a cube root. Because 5 × 5 × 5 = 125, ∛125 = 5.
Watch for
A bare check mark is not a radical symbol, and a colon or slash does not name a root.
Common mix-up
The symbol √25 names the principal square root 5, not both 5 and −5.
Exact meaning
The radical symbol √ marks a root. With no written index it denotes the principal square root; a small index, such as 3 in ∛, names another root.