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How to solve a formula for any variable on a TI-89 Titanium

By E-Code · updated

Press APPS and pick Numeric Solver, type the formula on the eqn: line (d=v*t+1/2*a*t^2) and ENTER, fill in the known letters, put the cursor on the unknown and press F2 (Solve). With d = 12, v = 2 and a = 4 it finds t = 2.

Step by step

  1. Open the apps. APPS Press APPS.
  2. Pick the Numeric Solver. 9 Press 9 for Numeric Solver. The cursor is on the eqn: line.
  3. Type the formula. ALPHA , = ALPHA 0 × T + 1 ÷ 2 × ALPHA = × T ^ 2 Type d=v*t+1/2*a*t^2. ALPHA , is d, ALPHA 0 is v and ALPHA = is a; T has its own key. Put * between letters.
  4. List the letters. ENTER Press ENTER. The solver lists d, v, t and a under the formula, the cursor on d.
  5. Give d and v. 1 2 ENTER 2 ENTER Type 12 ENTER for d (metres), then 2 ENTER for v (metres per second).
  6. Guess t, give a. 1 ENTER 4 ENTER Type 1 ENTER as a first guess for t, then 4 ENTER for a (the acceleration).
  7. Go to t. ▲ ▲ Press ▲ twice to put the cursor on t, the letter to solve for.
  8. Solve for t. F2 Press F2 (Solve). A ■ marks t and left-rt; left-rt = 0 means both sides match.
  9. Go home. HOME Press HOME. t keeps its value outside the solver too.
  10. Show t. T ENTER Type t and press ENTER.
  11. Read the answer. t = 2 seconds: 2·2 + ½·4·2² = 12. Put the cursor on any other letter and press F2 to solve for that one.

What the screen shows

t = 2 seconds: 2·2 + ½·4·2² = 12. Put the cursor on any other letter and press F2 to solve for that one.

Look for t 2. 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-89 calculator and each key lights up in turn as you press it.

Try “Solve a formula for any variable” on the TI-89 calculator

Related

Physics programs for the TI-89 Titanium:

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