Pretty easy question about squares of square roots

In summary, if you know that the square root of the sum of two numbers, a and b, is less than a given epsilon, then you can also conclude that both a and b are individually less than that same epsilon. This can be proven by squaring both sides of the inequality and taking square roots, or by considering the non-negativity of the left hand side and the values of a and b.
  • #1
AxiomOfChoice
533
1
If you know [itex]\sqrt{(a^2+b^2)} < \epsilon[/itex], do you know [itex]a < \epsilon[/itex] and [itex]b < \epsilon[/itex]? If so, how?
 
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  • #2
The left hand side of the first inequality is non-negative (I assume e > 0), so square both sides to get a^2 + b^2 < e^2. Now a^2 < e^2 - b^2 [itex]\leq[/itex] e^2 and if a > 0, take square roots. If a < 0, then it's obvious. Same for b.
 
  • #3
snipez90 said:
The left hand side of the first inequality is non-negative (I assume e > 0), so square both sides to get a^2 + b^2 < e^2. Now a^2 < e^2 - b^2 [itex]\leq[/itex] e^2 and if a > 0, take square roots. If a < 0, then it's obvious. Same for b.
Thanks. That's pitifully easy. I don't know why, but I have trouble taking square roots when inequalities are involved. I guess I start thinking about how, if you're working in the interval [itex][0,1][/itex], the square root of a number is bigger than the number itself, which gets confusing.
 

1. What is a square root?

A square root is a number that, when multiplied by itself, gives the original number. For example, the square root of 25 is 5, because 5 multiplied by itself equals 25.

2. What is a square of a square root?

A square of a square root is the result of multiplying a square root by itself. For example, the square of the square root of 9 is 9, because the square root of 9 is 3 and 3 multiplied by itself is 9.

3. How do you find the square of a square root?

To find the square of a square root, simply multiply the square root by itself using a calculator or by hand. For example, to find the square of the square root of 16, multiply 4 (the square root of 16) by 4, which equals 16.

4. Can a square root of a negative number have a real value?

No, a square root of a negative number does not have a real value. This is because when a negative number is multiplied by itself, it results in a positive number. Therefore, there is no real number that when multiplied by itself will give a negative number.

5. How are square roots and squares related?

Square roots and squares are inverse operations of each other. This means that taking the square root of a number and squaring a number will cancel each other out and give the original number. For example, the square root of 25 is 5, and 5 squared is 25.

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