Trident HelpOpen the calculator

Calculus

Find a definite integral

Work out the integral of a function between two x values and get a number.

Open in Trident

A definite integral adds up the area between the curve and the x-axis from a lower limit to an upper limit. Areas below the axis count as negative.

The calculator estimates it by adding up many thin slices, so the answer is a decimal (or a fraction when it happens to be exact).

Classic Graphing 84

Start on the main screen: Press 2nd then mode (QUIT) to get back to the home screen. Pressing clear on a menu also backs out of it.

  1. Open MATH and choose item 9, the integral function. It pastes fnInt(.

    math9

  2. Type X², a comma, X, a comma, the lower limit 0, a comma, the upper limit 1, and close the bracket.

    X,T,θ,nx²,X,T,θ,n,0,1)

  3. Press enter. The area under X² from 0 to 1 is one third.

    enter

You should seefnInt(X²,X,0,1) .3333333333

Classic Graphing 84 key reference

Natural Scientific 991

Start on the main screen: Press MENU, then 1 (Calculate) to return to the main calculation screen. AC clears the line you are on.

  1. Press the integral key to open the ∫ template.

    ∫

  2. Type the function x² (ALPHA and the bracket key give x), then move right to the lower limit and type 0, move right again and type 1.

    ALPHAx)x²▶0▶1

  3. Press = . The answer appears as the exact fraction 1/3.

    =

You should see∫(x²,0,1) 1/3

Press S⇔D afterwards to switch the fraction to the decimal 0.3333333333.

Natural Scientific 991 key reference

Natural Color Graphing

Start on the main screen: Press MENU then 1 to open Run-Matrix, the main calculation screen. Press EXIT to back out of a bar or screen, and SHIFT then EXIT (QUIT) to return to the app start.

  1. On the calculation screen press F4 for the MATH soft menu, then F4 again for ∫.

    F4F4

  2. Type X², then move right and enter the lower limit 0, move right and enter the upper limit 1.

    X,θ,Tx²▶0▶1

  3. Press EXE.

    EXE

You should see∫(X²,0,1) 1/3

Natural Color Graphing key reference

Tips

Related guides