Prove that a parametric equation's range is subset of a cartesian equation r(t)=t(t−2)^3i+t(t−2)^2j where r:RR to RR^2 C={(x,y) in RR^2∣y^4=x^3+2x^2y} I have difficulty with this question. This is where I am up to. 1) Find dy/dx of the cartesian curve dy/dx=(3x^2+4xy)/(4y^3−2x^2); 2) (4y^3−2x^2)=0,y=(2x^(2/3))/2; 3) Substitute y into cartesian equation and find x=-27/16,0.

sarahkobearab4

sarahkobearab4

Open question

2022-08-16

Prove that a parametric equation's range is subset of a cartesian equation
r ( t ) = t ( t 2 ) 3 i + t ( t 2 ) 2 j where r : R R 2
C = { ( x , y ) R 2 y 4 = x 3 + 2 x 2 y }
I have difficulty with this question. This is where I am up to.
Find d y / d x of the cartesian curve d y / d x = ( 3 x 2 + 4 x y ) / ( 4 y 3 2 x 2 )
( 4 y 3 2 x 2 ) = 0 , y = ( 2 x 2 / 3 ) / 2
Substitute y into cartesian equation and find x = 27 / 16 , 0
I'm not sure where to go from here, can anyone clarify if I am on the right track, thanks!

Answer & Explanation

Pasrbekwp

Pasrbekwp

Beginner2022-08-17Added 10 answers

I think you're making it too complicated.
If x ( t ) = t ( t 2 ) 3 and y ( t ) = t ( t 2 ) 2
then it's easy to show that y 4 = x 3 + 2 x 2 y
t 4 ( t 2 ) 8 = t 3 ( t 2 ) 9 + 2 t 2 ( t 2 ) 6 t ( t 2 ) 2
because the right side is t ( t 2 ) 8 [ t 2 ( t 2 ) + 2 t 2 ] = t ( t 2 ) 8 [ t 3 ] .

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