# Question: Product with Roots

## Comment on Product with Roots

### I did this a slightly

I did this a slightly different way and still got A. I didn't know the rule: x>0, then (√x)(√x)=x. So I did, (√49-√14+√14-√4) to get 7-2 = 5, and then √9-√3+√3-1 to get 3-1=2. Then I multiplied (5)(2) to get 10. So if x>0, can we also do (√x)(√x) = √(x)(x)? Thanks!
Yvonne ### Yes, that rule is definitely

Yes, that rule is definitely accurate. It's very similar to √(xy) = (√x)(√y)

### I solved it using the

I solved it using the different of two squares rule and came up with the right answer.

Is it correct? ### That's a perfectly valid

That's a perfectly valid approach. In fact, I think it's the best approach.

I don't cover that approach here, because the practice question appears very early in the module (just after the FOIL method video), so we haven't yet covered differences of squares.

### Can we simply identify the

Can we simply identify the principle (a^2 - b^2) = (a+b)(a-b), solving this way becomes easy. ### You're absolutely right. We

You're absolutely right. We can definitely use the Difference of Squares property to expand the expressions.

I don't cover that approach here, because the practice question appears very early in the module (just after the FOIL method video), so some student have not yet covered the Difference of Squares property.