Question

How do you simplify `(3sqrtx - sqrty)(sqrtx-4sqrty)`?

Answer 1

I found: `3x+4y-13sqrt(xy)`

Explanation:

We can try multiplying the two brackets (distribute) to get:
`(3sqrt(x)-sqrt(y))(sqrt(x)-4sqrt(y))=3sqrt(x)sqrt(x)-12sqrt(x)sqrt(y)-sqrt(x)sqrt(y)+4sqrt(y)sqrt(y)=`
we can now add similar terms (in `sqrt(x)sqrt(y)`) and use the fact that `sqrt(x)sqrt(x)=x` or `sqrt(y)sqrt(y)=y` and write:

`=3x-13sqrt(x)sqrt(y)+4y=3x+4y-13sqrt(xy)`

...that is as far I can go!