Problem Solving

A thin piece of wire 40 meters long is cut into tow pieces. one piece is used to form a circle with radius r, and the other is used to form a square. No wire is left over. Which of the following represents the total area, in meters, of the circular and the square regions in the term of r?
1 pi*r^2
2. pi*r^2 +10
3. pi*r^2 +1/4pi^2*r^2
4. pi*r^2+(40-2pi r)^2
5. pi*r^2+(10-1/2pi*r)2


If n is a multiple of 5 and n=p^2*q, where p and q are prime numbers, which of the following must be multiple of 25?
1. p^2
2. q^2
3. pq
4. p^2*q^2
5. P^3*q

Six machines , each working at the same constant rate, together can complete a certain job in 12 days. how many additional machines, each working at the same constant rate, will be needed to complete the job in 8 days.
1.2
2.3
3.4
4.6
5.8

For which of the following functions F is F(x)=F91-x) for all x?
1. f(x)=1-x
2. f(x)=1-x^2
3. f(x)=x^2-(1-x)^2
4. f(x)=x^2(1-x)^2
5. f(x)=x/(1-x)