Write the Word or Phrase That Best Completes Each Statement $f ( x ) = \sqrt { x ^ { 2 } + 1 }$

Short Answer

Write the word or phrase that best completes each statement or answers the question.
-s $f ( x ) = \sqrt { x ^ { 2 } + 1 }$ is defined on the interval $[ 0,4 ] .$ In (a) and (b), approximate the area under $f$ (to three decimal place follows:
(a) Partition $[ 0,4 ]$ into four subintervals of equal length and choose $u$ as the left endpoint of each subinterval.
(b) Partition $[ 0,4 ]$ into four subintervals of equal length and choose $u$ as the right endpoint of each subinterval.
(c) Use a graphing utility to approximate the actual area A.