For no solution, the two lines have to never intersect, which means they have to be parallel lines. In other words, no solution will satisfy both equation. For infinitely many solutions, the two lines have to overlap each other, which means one equation has to be a multiple of the other equations.
[joint] the site of the junction or union of two or more bones of the body; its primary function is to provide motion and flexibility to the frame of the body. Some are immovable, such as the sutures where segments of bone are fused together in the skull.
The skull can be divided into two main parts: the cranium and the mandible. The cranium is the largest part of the skull enclosing the brain, eyes, ears and nose. The mandible is the lower jaw, also known as the jaw bone. A human adult skull is made of 22 bones: 8 cranial bones and 14 facial bones. Except for the mandible, where the bones meet are ragged edges called sutures.