Answer:
1395 times.
Step-by-step explanation:
The Williams family open their door 28 + 17 = 45 times a day.
So in October they opened it 31 * 45 = 1395 times.
Answer:
???????????????????????????????????????
Answer:
2 / (x + 1).
Step-by-step explanation:
If the number is represented by x the expression is:
2 / (x + 1).
Answer:
Hyperbola.
Step-by-step explanation:
We start from the function:

We may get the traces if we cut the surface in planes x=k. This is equivalent to replace x for k:

The last equation is the equation of an hyperbola, which varies its characteristics depending on K (the plane cut).