Question
Question: The parametric representation of a parabola is x = 3 + t<sup>2</sup>, y = 2t – 1. Its focus is...
The parametric representation of a parabola is
x = 3 + t2, y = 2t – 1. Its focus is
A
(3, –1)
B
(3, 0)
C
(4, 0)
D
(4, –1)
Answer
(4, –1)
Explanation
Solution
x = 3 + t2, y = 2t –1
t2 = x – 3 
= t
= x – 3
(y + 1)2 = 4(x – 3)
Focus
X = 1, Y = 0
x – 3 = 1, y + 1 = 0
x = 4, y = –1
Ž (4, –1)