Which graph represents the parametric equations x = t^2 + 2t and y = –t, where –4 ≤ t ≤ 1?
2 answers:
Answer:
We have:
x = t^2 + 2*t
y = -t
where:
–4 ≤ t ≤ 1
Isolating t in the "y" equation, we get:
t = -y
Now we can use the limits of t, to find similar limits for y.
When t = -4
-4 = -y
4 = y
when t = 1
1 = -y
-1 = y
Then the limits for y are:
-1 < y < 4
Now, knowing that t = -y
we can replace that in the "x" equation:
x = t^2 + 2*t
x = (-y)^2 + 2*(-y)
x = y^2 - 2*y
Then the graph of the parametric equation is the one defined by:
x = y^2 - 2*y
in the range
-1 < y < 4
The graph of this can be seen below, where the two black dots are the points where the graph should start/end.
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