Question

Which of the following can be the parametric equation of
$(x-1{)}^2=-36(y-4)$

• A. $x=1+18t$ and$y=4-9t^2$
• B. $x=-1+18t$ and$y=-4-9t^2$
• C. $x=-1-18t$ and $y=4-9t^2$
• D. $x=1+18t$ and $y=-4-9t^2$

Answer 1

The correct option is A

$x=1+18t$ and$y=4-9t^2$

The parametric equation of
$x^2=-4ay$ are $x=2at$ and $y=-a{t}^2$

$\Rightarrow \text{For}(x-1{)}^2=-4\times 9(9-4)$,
it will be
$x-1=2\times 9\times t\text{and}y-4=-9t^2$

$\Rightarrow x=1+18t$ and $y=4-9t^2$