Answer:
always
Step-by-step explanation:
1+3+5+7+...+999 =
= 1+2+3+4+...+500
+1+2+3+...+499
= 2·(1+2+3+...+499) + 500
= 2·(499·500)/2 + 500
= 499·500 + 500
= 500·(499 + 1)
= 500·500
= 250.000
<span>You can use the fact that the work done is equivalent to finding the center of mass of the water in the tank(which is at the center of the cylindrical cross section, which is 3 ft below the level to which the liquid is pumped. Call this distance h.
You then need the total mass of the liquid, volume X density=m. This is where pi comes in!
Work needed =mgh, where g is the gravitational acceleration.</span><span>
</span>
Answer: (-2;8)
Step-by-step explanation:
