Solve the following inequality: x+y2+x−y2−1≤1.
It is known that a>1. Is it always true that ⌊⌊a⌋⌋=⌊4a⌋?
It is known that a=x+y+xy, b=y+z+yz, c=x+z+xz. where x>0, y>0, z>0. Prove that a+b+ab>c.