<p>pg. 642 BB # 17</p>
<p>
[quote]
In the xy-plane, line l passes through the origin and is perpendicular to the line 4x + y = k, where k is a constant. If the two lines intersect at the point (t , t + 1), what is the value of t?</p>
<p>A)-4/3
B)-5/4
C)3/4
D)5/4
E)4/3
[/quote]
The answer is A. I can't figure out what K equals, which is what is getting me stuck on this problem.</p>
<p>you don’t need to find ‘k’. You need to find the equation of line l.</p>
<p>Since l is perpendicular to the line y = k-4x, line l’s slope should be the negative reciprocal of this line.</p>
<p>Since this line’s slope is -4 , line l has a slope of 1/4, and since it passes through the origin and has to y-intercept, it’s equation is</p>
<p>y = (1/4)*x</p>
<p>Now plug in the points (t, t+1)</p>
<p>t+1 = t/4</p>
<p>4t+4 = t
3t = -4</p>
<p>t = -4/3</p>