Answer:
p= -1
Step-by-step explanation:
We have been given parabola along positive side of x-axis with equation

after equating the values of
we will get
4px =-4x
Divide each term by x on both left hand side and right hand side we will get
4p= -4
Now, divide each term by 4 on both left hand side and right hand side we will get the final result p=-1