Hi. This is about Unit 11 Integration fromIB Mathematics HL - Applications and Interpretations - OXFORD 2019. How do I use GDC to find the area?

Example 4 The region bounded by the graph of f(x) =x2 + 3, y the x-axis and the vertical lines x =-1 and x = a with a > -1 has area equal to 12. Find the value of a. International- mindedness A Riemann sum, named x=-1 X =a after 19th century German mathematician [ (x2 + 3) dx = 12 Bernhard Riemann, The unknown, a, is the upper bound approximates the area of this area. of a region, by adding a =2 First write down the definite integral. up the areas of multiple Use your GDC to find the value of a. simplified slices of the region. Exercise 11RExercise 11B 1 For each of the following: write down the definite integral that represents the area of the enclosed region. ii find the area. a y= x, the x-axis and the lines x = 2 and x = 4