Urgent ! this is very important me fast! how do you do: expand & simplify: (x 4)(x 2)
can you tell me how to work it out ?

So the question is asking: (x-4)(x-2)
because there is a bracket in between the two expressions it means we have to multiply them together: (x-4) x (x-2)

you can break down the question into smaller parts:
x multiply x
x multiply -2
-4 multiply x
-4 multiply -2

here are the answers:
x^2 (means x squared)
-2x
-4x
8 (because when you multiply two negative numbers it makes a positive)

now you put it into an expression (this is expanding):
x^2 - 2x - 4x + 8

to simplify it you collect like terms:
x^2 - 6x + 8

The above is the answer :)