Parabola 1 Question 11

11. The curve described parametrically by x=t2+t+1,y=t2t+1 represents

(a) a pair of straight lines

(b) an ellipse

(c) a parabola

(d) a hyperbola

Assertion and Reason

Show Answer

Answer:

Correct Answer: 11. (c)

Solution:

  1. Given curves are x=t2+t+1

and

y=t2t+1

On subtracting Eq. (ii) from Eq. (i),

Thus,

x=t2+t+1

x=xy22+xy2+1

4x=(xy)2+2x2y+4

(xy)2=2(x+y2)

x2+y22xy2x2y+4=0

Now, Δ=114+2(1)(1)(1)

1×(1)21×(1)24(1)2Δ

Δ0

Hence, it represents a equation of parabola.



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