TI-84 Plus Calculator's Math MATH Submenu
Press [MATH] to access the Math MATH submenu on the TI-84 Plus calculator. This submenu contains general mathematical functions you can insert into an expression.
Convert between decimals and fractions with the TI-84 Plus
The Frac function always converts a finite decimal to a fraction. Sometimes this function can convert an infinite repeating decimal to a fraction. When it can’t, it lets you know by redisplaying the decimal. Be sure to enter the decimal before inserting the Frac function, as shown in the first two lines of the first picture.
The Dec function converts a fraction to a decimal. Enter the fraction before you insert the Dec function.
Cube and take cube roots with the TI-84 Plus
The cube function, 3, cubes the value that precedes the function. The cube-root function,
finds the cube root of a value that follows the function. This value must be enclosed in parentheses; the calculator supplies the opening parenthesis; you must supply the closing parenthesis.
Take the xth root with the TI-84 Plus
The xth root function,
finds the xth root of the value that follows the function. To use this function, first enter the root x, then insert the
function, and then enter the argument. This is illustrated in the first image shown. In this example, the calculator is evaluating the fourth root of 16.
Find the location of maximum and minimum values
With the TI-84 Plus calculator, the fMin and fMax functions approximate where the minimum or maximum value of a function occurs in a specified interval. They do not compute the minimum or maximum value of the function; they just give you the x-coordinate of the minimum or maximum point.
The fMin and fMax functions are standalone functions in the sense that they cannot be used in an expression. To use these functions, insert the appropriate function, fMin or fMax, at the beginning of a new line on the Home screen. Then enter the definition of the function whose minimum or maximum you want to locate. Press [,] and enter the variable used in the definition of the function you just entered. Press [,] and enter the lower limit of the specified interval. Then press [,], enter the upper limit, and press [ ) ].
Finally, press [ENTER] to approximate the location of the minimum or maximum in the specified interval. This is illustrated in the second image shown. The calculator is approximating the location of the maximum value of the function x2 in the interval
Numerical differentiation and integration with the TI-84 Plus
The calculator cannot perform symbolic differentiation and integration. For example, it cannot tell you that the derivative of x2 is 2x, nor can it evaluate an indefinite integral. But the nDeriv function will approximate the derivative (slope) of a function at a specified value of the variable, and the fnInt function will approximate a definite integral.
Insert the nDeriv function, enter the function whose derivative you want to find, and then press [,]. Enter the variable used in the definition of the function you just entered and press [,]. Then enter the value at which the derivative is to be taken, and press [ ) ]. Finally, press [ENTER] to approximate the derivative. This is illustrated in the third image.
To use the fnInt function, insert fnInt, and then enter the function you are integrating. Press [,] and enter the variable used in the definition of the function you just entered. Press [,] and enter the lower limit of the definite integral. Press [,], enter the upper limit, and press [ ) ]. Finally, press [ENTER] to approximate the definite integral.
The calculator may give you an error message or a false answer if nDeriv is used to find the derivative at a nondifferentiable point or if fnInt is used to evaluate an improper integral.