# Thread: Finding equation of curve

1. ## Finding equation of curve

Could someone please help me with this question?
Find the equation of curve COD, assuming it is of the form y = ax^2n
points are C(-60,18) O(0,0), D(40,8)
ive read some help for this question, but they mostly just say sub in the points and solve simultaneously
ive tried this and i really need help with actually finding n and a, i have subbed in the points but i really dont no what do from there
if anyone could help me with this question it would be much appreciated ! =D

2. Originally Posted by flyinhigh123
Could someone please help me with this question?
Find the equation of curve COD, assuming it is of the form y = ax^2n
points are C(-60,18) O(0,0), D(40,8)
ive read some help for this question, but they mostly just say sub in the points and solve simultaneously
ive tried this and i really need help with actually finding n and a, i have subbed in the points but i really dont no what do from there
if anyone could help me with this question it would be much appreciated ! =D
Substitute (-60, 18): $18 = a (-60)^{2n}$ .... (1)

Substitute (40, 8): $8 = a (40)^{2n}$ .... (2)

Divide equation (1) by equation (2), simplify and solve for n. Use that value of n to substitute into one of the equations and solve for a.

3. thanxx but im still having a little trouble =((

i got
18/8 = [(-60)^2n]/(40)^2n]
cause the a cancels out

and then i dont really no wat to do next
how do i simplify that?

4. Originally Posted by flyinhigh123
thanxx but im still having a little trouble =((

i got
18/8 = [(-60)^2n]/(40)^2n]
cause the a cancels out

and then i dont really no wat to do next
how do i simplify that?
$\frac{9}{4} = \left( - \frac{60}{40} \right)^{2n}$

$\Rightarrow \frac{9}{4} = \left( \left( - \frac{3}{2} \right)^{2}\right)^n$

$\Rightarrow \frac{9}{4} = \left(\frac{9}{4}\right)^n$

$\Rightarrow n = 1$.