- #1

- 466

- 5

$$\sqrt{\int f(x)dx}$$ right?

i did an example problem and they turned out not to be equivalent but i just wanted to make certain.

if they actually aren't equivalent.. why aren't they???

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- Thread starter iScience
- Start date

- #1

- 466

- 5

$$\sqrt{\int f(x)dx}$$ right?

i did an example problem and they turned out not to be equivalent but i just wanted to make certain.

if they actually aren't equivalent.. why aren't they???

- #2

- 466

- 5

well, better example:

$$\sqrt{(C\int\sqrt{(a+b)}dx)^2}$$

this is not the same as..

$$\sqrt{C^2\int(a+b)dx}$$

is it?

(C= constant, a= variable, b=constant (not that it really matters..))

$$\sqrt{(C\int\sqrt{(a+b)}dx)^2}$$

this is not the same as..

$$\sqrt{C^2\int(a+b)dx}$$

is it?

(C= constant, a= variable, b=constant (not that it really matters..))

Last edited:

- #3

- 17,491

- 9,223

$$\sqrt{\int f(x)dx}$$ right?

i did an example problem and they turned out not to be equivalent but i just wanted to make certain.

if they actually aren't equivalent.. why aren't they???

Try ##f(x)=x^2## and you'll see for yourself why they are not the same.

- #4

- 575

- 76

In this case, if you remember that ##\sqrt{a+b}\neq\sqrt{a}+\sqrt{b}## most of the time, and in general ##\sqrt{\sum_1^n a_i}\neq\sum_1^n\sqrt{a_i}##, it's not too hard to see why, most of the time, ##\sqrt{\int_a^bf(x)\ dx}\neq\int_a^b\sqrt{f(x)}\ dx##.

- #5

- 466

- 5

In this case, if you remember that ##\sqrt{a+b}\neq\sqrt{a}+\sqrt{b}## most of the time, and in general ##\sqrt{\sum_1^n a_i}\neq\sum_1^n\sqrt{a_i}##, it's not too hard to see why, most of the time, ##\sqrt{\int_a^bf(x)\ dx}\neq\int_a^b\sqrt{f(x)}\ dx##.

Thanks this was helpful! :)

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