A solar model is used to calculate the expected temperature and density at all depths within the Sun. These results are then used to calculate the expected fusion rate within the Sun. We have confidence that the model is correct because it agrees with the observed characteristics of the Sun. Which of the following observations can be used to check that we really do know the Sun’s internal fusion rate?.
A. Measurements of the varying number of sunspots on the Sun over time.
B. Measurements of the Sun’s total energy output into space.
C. Observations of neutrinos coming from the Sun.
D. Observations of the total X-ray emission from the Sun’s corona.
E. Measurement of the Sun’s mass

russian is not my first language, so i'm afraid i can't write out an answer in russian, but hopefully you can find a way to do so. here's my best translation of the problem: you're given a plot of a particle's position in one-dimensional space over time, and you're asked to find either the total distance traveled by the particle after 6 seconds had elapsed, or the total displacement of the particle after 6 seconds.

if you want the total distance traveled, you would first need to determine the particle's velocity as a function of time, then integrate that over the 6-second interval. we know the position function is quadratic with roots at 0 and 6, so we have

where is unknown. because the position is parabolic, there is symmetry about the midpoint at , and we know that

so that the position function is

which means the velocity is

then the total distance traveled is

so the total distance traveled is 20 m.

on the other hand, if you want to find displacement: the particle starts at and ends at , so its displacement is 0.