Q.7, What is piece-wise function and modulus function ?

Lesson#29
Example 1 on page # 9
Question # 7 of Ex. 1.1
Q. 7 :
Show that the parametric equations.
( i ) x = at(2)
y = 2at
Represent the equation of parabola
y(2) = 4ax
mathematics
chapter no 1