In xy coordinate system, the straight line L 1 crosses the origin and is perpendicular to the straight line L2:4x+y=k, where k is a constant. If two straight lines intersect at point (t, t+ 1), find the value of t.

solve

The straight line L 1 is perpendicular to L2, and the slope of L2 is -4.

The slope of = =>L 1 is 1/4.

And L 1 crosses the origin.

The equation of = =>L 1 line is y=? x

L 1 and L2 intersect at point (t, t+ 1).

= = & gtt+ 1=？ t……①

4t+(t+ 1)=k……②

= = & gtt=-4/3，k=- 17/3