Are 2.7, 3.6, and 4.5 a pythagorean triple

They are because 2.7 squared + 3.6 squared = 4.5 squared (=20.25) 

Pythagoras Theorem is that a squared + b squared = c squared 

So the 2 smallest numbers squared will equal the larger one squared if it is a pythagoreom triple

Aquadratic function is one of the form f(x)=ax2 + bx + c l, where a,b, and c are numbers with are not equal to zero.