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1976 MMPC , Part 2 = Michigan Mathematics Prize Competition

p1. The total cost of 11 football, 33 tennis balls and 77 golf balls is $14\$14 , while that of 11 football, 44 tennis balls and 1010 golf balls is $17\$17.If one has $20\$20 to spend, is this sufficient to buy a) 33 footballs and 22 tennis balls? b) 22 footballs and 33 tennis balls?
p2. Let AB\overline{AB} and CD\overline{CD} be two chords in a circle intersecting at a point PP (inside the circle). a) Prove that APPB=CPPDAP \cdot PB = CP\cdot PD. b) If AB\overline{AB} is perpendicular to CD\overline{CD} and the length of AP\overline{AP} is 22, the length of PB\overline{PB} is 66, and the length of PD\overline{PD} is 33, find the radius of the circle.
p3. A polynomial P(x)P(x) of degree greater than one has the remainder 22 when divided by x2x-2 and the remainder 33 when divided by x3x-3. Find the remainder when P(x)P(x) is divided by x25x+6x^2-5x+6.
p4. Let x1=2x_1= 2 and xn+1=xn+(3n+2)x_{n+1}=x_n+ (3n+2) for all nn greater than or equal to one. a) Find a formula expressing xnx_n as a function ofn n. b) Prove your result.
p5. The point MM is the midpoint of side BC\overline{BC} of a triangle ABCABC. a) Prove that AM12AB+12ACAM \le \frac12 AB + \frac12 AC.
b) A fly takes off from a certain point and flies a total distance of 44 meters, returning to the starting point. Explain why the fly never gets outside of some sphere with a radius of one meter.
PS. You should use hide for answers. Collected [url=https://artofproblemsolving.com/community/c5h2760506p24143309]here.