Answer:
Step-by-step explanation:
The first expression you are trying to find is
x2+y2
but this can be cast as
(x+y)2−2xy
so we can easily see that the result, given our input data, is
(2)2–2⋅4=4–8=−4
To obtain x3 we can do the following
x⋅(x2+y2)=x⋅−4=−4x=x3+xy⋅y=x3+xy⋅y
this can be re-arrange to be
x3=−4x−4y=−4(x+y)=−4⋅2=−8
The result is
x2+y2=−4
x3=−8