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How to add up a Riemann sum on a TI-84 Plus CE or TI-84 Plus

By E-Code · updated

Press 2nd LIST, ▶▶ to MATH and 5 for sum(, then 2nd LIST, ▶ to OPS and 5 for seq(: its form asks for Expr, Variable, start, end and step (X²*.5, X, 0, 1.5, .5), and Paste puts it after sum(. Close with ) and press ENTER: 1.75.

Step by step

  1. Open LIST. 2nd STAT Press 2nd, then STAT. LIST (above STAT) has NAMES OPS MATH.
  2. Go to MATH. ▶ ▶ Press ▶ twice to the MATH tab.
  3. Pick sum(. 5 Press 5 for sum(: it adds up a list.
  4. LIST again. 2nd STAT Press 2nd, then STAT.
  5. Go to OPS. ▶ Press ▶ once to the OPS tab.
  6. Pick seq(. 5 Press 5 for seq(. A form opens (a stat wizard) with Expr, Variable, start, end and step.
  7. One rectangle's area. X,T,θ,n X² × . 5 ENTER Type X² × .5 and press ENTER: height X² times width 0.5.
  8. The variable. X,T,θ,n ENTER Type X,T,θ,n and press ENTER: X moves along the rectangles.
  9. First and last left edge. 0 ENTER 1 . 5 ENTER Type 0, ENTER, then 1.5, ENTER: X runs from 0 to 1.5.
  10. The step. . 5 ENTER Type .5 and ENTER: steps of 0.5, the left edges of 4 rectangles from 0 to 2. The cursor is on Paste.
  11. Paste it. ENTER Press ENTER. seq( with your entries lands after sum( on the home screen.
  12. Close sum(. ) Press ) to close sum(.
  13. Add them up. ENTER Press ENTER.
  14. Read the sum. 1.75: the left Riemann sum of X² from 0 to 2 with 4 rectangles. The exact area is 2.667; smaller steps get closer.

What the screen shows

1.75: the left Riemann sum of X² from 0 to 2 with 4 rectangles. The exact area is 2.667; smaller steps get closer.

Look for 1.75 on the screen.

Try it with the keys lit up

This guide is one of E-Code's Learn lessons. Open it on E-Code's TI-84 calculator and each key lights up in turn as you press it.

Try “Add up a Riemann sum” on the TI-84 calculator

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