posted by Kate .
The top of a 15-foot ladder is 3 ft. father up a wall than the foot of the ladder is from the bottom of the wall. How far is the foot of the ladder from the bottom of the wall?
Let x be the distance of the foot from the wall. Then use the Pythagorean theorem.
x^2 + (x+3)^2 = 15^2 = 225
2x^2 +6x -216 = 0
x^2 +3x -108 = 0
That factors easily. (Think: 9x12 = 108)Take the positive root.