Question

Compute d2y/dx2 at the point(2,2) x^2+y^2=8

Answer 1

Can you take dy/dx?

Answer 2

i did take dy/dx. i got 2x+ 2y dy/dx=0 that led to -2x/2y=-1

Answer 3

i dont know how to do it the 2nd time

Answer 4

It's correct dy/dx = - x/y

Answer 5

hmm k i get -y + xdy/dx/y^2

Answer 6

(y + xdy/dx)/y^2

Answer 7

wait is the answer 3

Answer 8

Correct!

Answer 9

but its not any of the answer choices

Answer 10

the choices are
a)-3
b)1
c)2
d) -1
e)-2

Answer 11

Hold, I think you have wrong sign!

Answer 12

= 2 - 2 ( -1) / 2^2
= 4/4 = 1

Answer 13

hmm k. i hope its correct

Answer 14

Math has the numbers, it's NOT hope!

Answer 15

You're correct at derivative, but somehow you miscalculated at last step!

Answer 16

k. thanks!

Answer 17

it was wrong :(

Answer 18

y'=(-x/y) then y''=(-y+xy')/y^2 then y''=(-y-x^2/y)/y^2=-(x^2+y^2)/y^3=-8/y^3=-1

Answer 19

@mahmit2012's result is right!
I have worked out on it to check the plug in :
y" = ( -y + xy' ) / y^2
= -2 +2 ( -1) / 4 = - 4/ 4 = -1

Answer 20

yes but i wanted to show in this case (circle equation)we have y''=-R^2/y^3 R is radiant of circle