Here's the question you clicked on:
nexis
Weighted Averages: http://ocw.mit.edu/courses/mathematics/18-01sc-single-variable-calculus-fall-2010/part-c-average-value-probability-and-numerical-integration/session-61-integrals-and-weighted-averages/MIT18_01SCF10_ex61sol.pdf On Page 2, we find the y-coordinate of the centroid. My question is 1) why do we add up the right and the left side after solving for y 2) wouldn't adding the left and right side yield 2+sqrt(x) and not 2sqrt(x)?