4x^2+20x+5y+xy

*you have to factor by grouping,for more information just ask me*

First, take out 4x from the first two and y from the second:
4x(x+5) + y(x+5).
Then combine the 4x and the y:
(4x+y)(x+5).
That's your answer.

thanks. - can you help me with this one?
*48x^2y+20xz+12xy+5z

First, you should notice that 12*4=48 and 5*4 is 20. So, rearrange a little:
12xy + 48x^2y + 5z + 20xz.
Then, take out 12xy from the first two and 5z from the second two:
12xy(4x+1) + 5z(4x+1).j
Combine:
(12xy+5z)(4x+1).

thank you;please help me with my other problems...