Which of the following collections of subsets of the plane, R2 , are partitions?
(a) {{(x; y) | x + y = c}| c  R}
(b) The set of all circles in R2
(c) The set of all circles in R2
centered at the origin together with the set {(0; 0)}
(d) {{(x; y)} | (x; y)  R
2
}

14 pointslet x be the seats in the small van and y the seats in the large van. how many seats does the large van have? a company uses two vans to transport worker from a free parking lot to the workplace between 7: 00 and 9: 00a.m. one van has 9 more seats than the other. the smaller van makes two trips every morning while the larger one makes only one trip. the two vans can transport 69 people, maximum.how many seats does the larger van have?

Look at arnold's attempt to solve the equation for b: 3b = 12 b = 3 · 12 b = 36 describe the mistake that arnold made.

Complex numbers multiply √-4 * √-25 and show all intermediate steps. alternative notation is sqrt(-4) * sqrt(-25).