# Category: TI 84 Plus techniques

## How to graph X given Y

Example 1: Volume of revolution in 2017 alevel P2 4b

Let a=2 so we can visualise the shape of the graph

Example 2: Solution curve for Differential equation. 2014 alevel P1

This is solution for part iv.

It can be sketched without expressing the solution in the form x=f(t)

## How to sketch both cartesian and parametric graphs on the same diagram using GC

**Example 1**

DHS J1 2018 Aug Test

Suppose we want to sketch the curve C and the line y=-2x+2 on the same graph

Note how the line y-2x+2 is entered.

Adjust the Tmax to 1% more so the graph displays correctly.

**Example 2**

2011 alevel P1 Q11

## Sketching Periodic functions with GC

Suppose we want to sketch the graph from -3 to 8.

- Enter by pressing “Math, Piecewise”.

2. Adjust the window setting to the required domain.

3. Trace the end point at -3 since it is not 1 complete cycle.

## Functional differences between TI 84 Plus CE and TI 84 Plus C for h2 maths

The following comparison are based on

TI 84 CE: Operating system 5.3.0

TI 84 Plus C: Operating system 4.2

Singapore Approved Operating System

**Division of complex numbers**in TI 84 Plus CE can be entered in fractions, whereas it must be entered using division in TI 84 Plus C

.

**Piecewise function**is now available in TI 84 Plus CE. This command can be found under MATH B: piecewise ( . Piecewise function can also be created manually in TI 84 Plus C but slightly more tedious.

New CONDITIONS submenu in “2nd test” allows faster entry of intervals for the piecewise functions

- Inverse binomial distribution and inverse norm enhancement in TI 84 CE

- Store tangent and faster access to n/d template in TI 84 CE

**Conclusion**

There are no major functional differences between TI 84 Plus CE and TI 84 Plus C. For piecewise functions, students should learn how to sketch manually without using the GC.

## Checking Differential equation using GC

GC can be used to check the solution to differential equation.

**Example from 2014 P1 Q10**

Suppose we want to check whether the following solution to 10 iv is correct:

Enter the following in GC

Since Y2 and Y3 gave the same values, the solution is correct.

## Using GC to calculate Expectation and Variance of Discrete Random Variable

**Example 1**

**Solution**

Enter the data in the GC as follows:

Variance can also calculated using the GC as follows:

**Example 2**

RI 2018 J2 MYE Q13i

## GC setting for faster graph plot

**Method 1: Change Xres to 3**

The Xres button refers to pixel resolution (1 through 8). At Xres = 1, functions are evaluated and graphed at each pixel on the x-axis. At Xres = 8, functions are evaluated and graphed at every eighth pixel along the x-axis. Small Xres values improve graph resolution but may cause the calculator to draw graphs more slowly. Setting Xres to 3 provides good balance between speed and resolution.

**Example**

**Xres= 1**

Time taken to plot= 23.4 s

**Xres= 3**

Time taken to plot= 3.6 s

Savings of almost 20 seconds! Which is crucial in exams

**Method 2: Turn off “Detect Asymptotes”**

## Using GC to find the Normal vector to planes

## Using GC in Differential Equations

The following example illustrates how we can use GC in Differential equations, and avoid the need to do integration to solve differential equation.

**Solution for part ii**