MathDB
Line Family

Source: 1988 National High School Mathematics League, Exam Two, Problem 3

February 25, 2020
analytic geometrygraphing linesslope

Problem Statement

On the coordinate plane, is there a line family of infinitely many lines l1,l2,,ln,l_1,l_2,\cdots,l_n,\cdots, satisfying the following? (1) Point(1,1)ln(1,1)\in l_n for all nZ+n\in \mathbb{Z}_{+}. (2) For all nZ+n\in \mathbb{Z}_{+},kn+1=anbnk_{n+1}=a_n-b_n, where kn+1k_{n+1} is the slope of ln+1l_{n+1}, an,bna_n,b_n are intercepts of lnl_n on xx-axis, yy-axis. (3) knkn+10k_nk_{n+1}\geq0 for all nZ+n\in \mathbb{Z}_{+}.