Answer:
W1 = W2 = 50k Joules (assuming W1 and W2 have the same force constant, k)
W1 - W2 = 0
Step-by-step explanation:
Work done in stretching a spring is given by 1/2ke^2
Where, k is force constant and e is extension
e1 = 30cm - 20cm = 10cm
W1 = 1/2k(e1)^2 = 1/2×k×10^2 = 50k Joules
e2 = 40cm - 30cm = 10cm
W2 = 1/2k(e2)^2 = 1/2×k×10^2 = 50k Joules
W1 = W2 = 50k Joules provided W1 and W2 have equal force constant
Therefore, W1 - W2 = 0
When x=-1:

Ok that gives us a little more information.
If we implicitly differentiate with respect to t, from the very start, then we can apply our product rule, ya?

The right side is zero, derivative of a constant is zero.
Where x' is dx/dt and y' is dy/dt.
From here, plug in all the stuff you know:
y' = -3
x = -1
y = 4
and solve for x'.
Hope that helps!
? Ummm What is the question???
Answer:
7 pizzas and 9 cans of juice
Step-by-step explanation:
The answer is 7 pizzas because if you add the 25 people plus her parents (That would be two more people) is 27. Then you have to multiply 27×2 that would equal 54. So, now you know you need 54 slices but what you is the amount of pizzas needed. The next step would be to divide 54÷8 that would equal 6.75 but you can't buy 6.75 pizzas, and you can't buy 6 pizzas because than you would leave people outside. You will need to buy 7 pizzas. It is better to have left overs than leaving people outside.
For the amount of cans would be 9 because if you add again 25 people plus her parents it would be 27. Then you multiply 27×1 that is obviously 27. The next step would be to divide 27÷3 and it would equal 9. And that is how you get your answer.