Maths Olympiad Prep

Library / /179 of 520

Geometry Difficulty 6.7 National olympiad Find the answer

A hyperbola in the coordinate plane passing through the points (2,5)(2,5), (7,3)(7,3), (1,1)(1,1), and (10,10)(10,10) has an asymptote of slope 2017\frac{20}{17}. The slope of its other asymptote can be expressed in the form mn-\frac{m}{n}, where mm and nn are relatively prime positive integers. Compute 100m+n100m+n.

Proposed by Michael Ren

A number or a short expression. Fractions can be typed as 3/2, and spacing doesn't matter.

Solution

To solve this problem, we need to find the slope of the other asymptote of the hyperbola. Given that the hyperbola passes through the points (2,5)(2,5), (7,3)(7,3), (1,1)(1,1), and (10,10)(10,10), and has one asymptote with a slope of 2017\frac{20}{17}, we can use properties of hyperbolas and their asymptotes to find the slope of the other asymptote.

1. Identify the slopes of the asymptotes:
The slopes of the asymptotes of a hyperbola are given by ±ba\pm \frac{b}{a} or ±ab\pm \frac{a}{b}, depending on the orientation of the hyperbola. Since we are given one slope as 2017\frac{20}{17}, we can denote the slopes of the asymptotes as 2017\frac{20}{17} and mn-\frac{m}{n}.

2. Use the property of hyperbolas:
For a hyperbola, the product of the slopes of the asymptotes is always 1-1. This is because the asymptotes are perpendicular to each other in the coordinate plane.

(2017)(mn)=1 \left(\frac{20}{17}\right) \left(-\frac{m}{n}\right) = -1

3. Solve for the unknown slope:
Substitute the given slope into the equation and solve for mn\frac{m}{n}:

2017mn=1 \frac{20}{17} \cdot -\frac{m}{n} = -1

20m17n=1 \frac{20m}{17n} = 1

20m=17n 20m = 17n

mn=1720 \frac{m}{n} = \frac{17}{20}

Therefore, the slope of the other asymptote is 1720-\frac{17}{20}.

4. **Express the slope in the form mn-\frac{m}{n}:**
Here, m=17m = 17 and n=20n = 20. These are relatively prime positive integers.

5. **Compute 100m+n100m + n:**
Substitute mm and nn into the expression 100m+n100m + n:

100m+n=10017+20=1700+20=1720 100m + n = 100 \cdot 17 + 20 = 1700 + 20 = 1720

The final answer is 1720\boxed{1720}.

Want a route through all this instead of an archive? The track puts 2,000 problems in a working order, from AMC 10 level to the IMO shortlist.

Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic and difficulty added by this site.