Final answer:
The civilizations that influenced Greek mathematics were Egyptian and Mesopotamian.
Step-by-step explanation:
The civilizations that are believed to have influenced Greek mathematics are Egyptian and Mesopotamian. Egyptian mathematics, documented in papyri such as the Rhind Mathematical Papyrus, showed advanced knowledge of algebra and geometry. They had also solved problems involving the Pythagorean theorem and quadratic equations. Similarly, the Babylonians had knowledge of the relationship between the sides and hypotenuse of a right triangle, as demonstrated by a clay tablet known as Plimpton 322. These mathematical ideas and techniques likely influenced Greek mathematicians such as Pythagoras.