Question

How is the following simplified? Is cross multiplication used?

`(a/b+c/d)`

Answer 1

Well. to simplify it we'll need to make those denominators common
`(axxd)/(bxxd)+(cxxb)/(d xx b)`
You get
`(ad)/(bd)+(cb)/(bd)`
You get
`(ad+cb)/(bd)`
And no... cross multiplication is used in when there are equations... not terms....well terms made up equations but when there are only terms.. we don't use cross multiplication
For example... if it was
`a/b=c/d`
Then you could cross multiply and come up with
`ad=cb`

Answer 2

When we add fractions we need a common denominator.

`a/b + c/d = {ad}/{bd} + {bc}/{bd} = {ad + bc}/{bd}`

Explanation:

I suppose you could call the resulting numerator a cross multiplication, but I'm not really sure what that means.

The important thing is to be able to add fractions by finding the common denominator. That's often the product of the denominators. However if the denominators have a common factor a simpler common denominator can be found.