Step by step
The question
Question: find the 4th root of 81.
4√81
The small 4 says how many times.
The 4th root of 81 asks: which number, times itself 4 times, makes 81?
? × ? × ? × ? = 81
1 List the 4th powers
4th powers are a number times itself 4 times.
2 × 2 × 2 × 2 is 16.
3 × 3 × 3 × 3 is 81.
4th powers: 24 = 16, 34 = 81
81 is in the list: 3 × 3 × 3 × 3 is 81.
3 × 3 × 3 × 3 = 81
So the 4th root of 81 = 3.
= 3
2 Check
Let's check: 3 times itself 4 times.
We get 81.
So the answer is right!
3 × 3 × 3 × 3 = 81
Let's look back.
First: list the 4th powers.
Last: check.
Answer
= 3