Математика 10-11 класс геометрия

y = √x
4 ≤ x ≤ 9
S = ∫₄⁹ √x dx
  = ∫₄⁹ x^(1/2) dx
  = [ x^(3/2) / (3/2) ]₄⁹
  = (2/3) [ x^(3/2) ]₄⁹
  = (2/3)( 9^(3/2) − 4^(3/2) )
  = (2/3)( 27 − 8 )
  = (2/3)⋅19
  = 38/3