When posting questions, please use the spoiler function to hide the correct answer. This will allow others to attempt the question without seeing the final answer.Nijo wrote:If xy + z = x(y+z), which of the following must be true?
A) x =0 and z =0
B) x=1 and y =1
C) y=1 and z =0
D) x=1 or y=0
E) x =1 or z=0
The key word here is must.
Given: xy+z = x(y+z)
Expand: xy+z = xy + xz
Subtract xy from both sides: z = xz
Rearrange: xz - z = 0
Factor: z(x-1) = 0
This tells us that z = 0 or x = 1
Answer: E
Cheers,
Brent
