Find work from additional spring compression

[Sneakatone]

The spring used has a spring constant of k= 35000 N/m.
a) how much work must you do to compress this spring by 0.10 m from its relaxed condition.
U=1/2*k*x^2
.5*35000*(0.1)^2=175 J (correct)

b)how much work must you do to compress the spring an additional 0.10 m?
I tried the same equation but with x=0.2 but it doesn't work. (U=700J)

 

[Doc Al]

b)how much work must you do to compress the spring an additional 0.10 m?
I tried the same equation but with x=0.2 but it doesn't work. (U=700J)

I assume they want how much additional work you must do.

 

[Sneakatone]

Ohhh
I subtracted 700-175 and its correct , Thanks!