# "We are given:" #
# \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad \ F(x) = int_0^x \ sqrt{ t^3 + 1 } \ dt. #
# "So, directly by a Fundamental Theorem of Calculus, we have" #
# "at once:" #
# \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad \ F'(x) = sqrt{ x^3 + 1 }. #
# "Thus:" #
# \qquad \qquad \qquad \qquad \qquad \qquad F'(2) = sqrt{ 2^3 + 1 } = sqrt{ 9 } = 3. #
# "So:" #
# \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad \qquad F'(2) = 3. #