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Subcontests

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1963 MMPC , Part 2 = Michigan Mathematics Prize Competition

p1. Suppose x1x \ne 1 or 1010 and logarithms are computed to the base 1010. Define y=1011logxy= 10^{\frac{1}{1-\log x}} and z=11logyz = ^{\frac{1}{1-\log y}} . Prove that x=1011logzx= 10^{\frac{1}{1-\log z}}
p2. If nn is an odd number and x1,x2,x3,...,xnx_1, x_2, x_3,..., x_n is an arbitrary arrangement of the integers 1,2,3,...,n1, 2,3,..., n, prove that the product (x11)(x22)(x33)...(xnn)(x_1 -1)(x_2-2)(x_3- 3)... (x_n-n) is an even number (possibly negative or zero).
p3. Prove that 135(2n1)246(2n<12n+1\frac{1 \cdot 3 \cdot 5 \cdot \cdot \cdot (2n-1)}{2 \cdot 4 \cdot 6 \cdot \cdot \cdot(2n} < \sqrt{\frac{1}{2n + 1}} for all integers n=1,2,3,...n = 1,2,3,...
p4. Prove that if three angles of a convex polygon are each 60o60^o, then the polygon must be an equilateral triangle.
p5. Find all solutions, real and complex, of 4(x2+1x2)4(x+1x)7=04 \left(x^2+\frac{1}{x^2} \right)-4 \left( x+\frac{1}{x} \right)-7=0
p6. A man is 38\frac38 of the way across a narrow railroad bridge when he hears a train approaching at 6060 miles per hour. No matter which way he runs he can just escape being hit by the train. How fast can he run? Prove your assertion.

PS. You should use hide for answers. Collected [url=https://artofproblemsolving.com/community/c5h2760506p24143309]here.