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A graphing calculator is an indispensable tool for students, educators, and professionals who need to evaluate integrals quickly and accurately. Beyond graphing, these devices can solve equations, compute derivatives, and—most importantly—calculate definite integrals that represent the area under a curve or between two curves.
1. Press the Math button.
2. Navigate to the fnInt( function from the menu. The calculator screen will display fnInt( with a blinking cursor after the opening parenthesis.
Enter the function that bounds the region, followed by a comma. For example, to find the area under f(x)=x² above the x‑axis, type x²,. The screen should read fnInt(x²,.
Next, type the variable of integration and a comma: fnInt(x²,x,. Then input the lower bound of the interval. If the interval starts at 3, the display will show fnInt(x²,x,3,.
Finally, enter the upper bound and close the parenthesis. For an upper bound of 7, the full expression becomes fnInt(x²,x,3,7).
When the region is bounded by two curves, input the top curve, a minus sign, and the bottom curve, then a comma. For instance, to find the area between y=x² and y=x/4, type x²-x/4,. Continue with the variable, lower bound, upper bound, and closing parenthesis as shown above.
Press Enter to evaluate the integral. Within a few seconds, the calculator displays the numerical area. The result is the exact measure of the region’s area in the chosen units.
