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How to solve a differential equation on a TI-89 Titanium

By E-Code · updated

Press F3, then ALPHA ) for C:deSolve(, type the equation with 2nd = for ′ (y′ is the derivative of y), then the input letter and the unknown: deSolve(y′=y,x,y) gives y=@1·ℯ^x, where @1 is any number.

Step by step

  1. Pick deSolve(. F3 ALPHA ) Press F3 for Calc, then ALPHA ) for C:deSolve(. Menu items after 9 are letters, and C is the ALPHA letter on the ) key.
  2. Type y′=y. Y 2nd = = Y Type y, then 2nd = for ′ (prime). y′ means the derivative of y. Then type =y.
  3. Name the letters. , X , Y ) Type a comma, x, a comma, y and ). That is: x is the input letter, and y is the unknown function of x.
  4. Solve it. ENTER Press ENTER.
  5. Read the solution. y = @1·ℯ^x: @1 stands for any number, so every C·ℯ^x is its own derivative. Add and y(0)=… to pin down @1.

What the screen shows

y = @1·ℯ^x: @1 stands for any number, so every C·ℯ^x is its own derivative. Add and y(0)=… to pin down @1.

Look for y=@1·ℯ^x 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 differential equation” on the TI-89 calculator

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Math programs for the TI-89 Titanium:

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