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 ̃(y + 1) / 2 = t ̃ (y + 1)2 = 4(x – 3)
Y2 = 4X focus X = 1, Y = 0
x – 3 = 1, y + 1 = 0 ̃ x = 4, y = – 1 ̃ (4, –1)