How to Put Log Into Calculator Ti-84

Introduction

The logarithm function is the inverse of the exponential function. It answers the question: "To what power must a base number be raised to obtain a given number?" The TI-84 calculator provides two main logarithmic functions:

• Common logarithm (log): Uses base 10
• Natural logarithm (ln): Uses base e (approximately 2.71828)

These functions are essential in various fields including mathematics, physics, engineering, and finance.

Accessing the Log Function

To access the logarithm functions on your TI-84 calculator, follow these steps:

1. Turn on your TI-84 calculator and press the 2ND key.
2. Locate the LOG button (it's labeled as "log" on the screen).
3. For the natural logarithm, press the LN button (labeled as "ln" on the screen).

Using the Log Function

Once you've accessed the log or ln function, you can use it in calculations in several ways:

Direct Calculation

To calculate a simple logarithm:

1. Press the 2ND key.
2. Press the LOG or LN button.
3. Enter the number you want to find the logarithm of.
4. Press the = key to see the result.

In Equations

You can use the log function in equations:

1. Set up your equation using the log function.
2. Use the ALPHA key to enter variables if needed.
3. Press the = key to solve.

Common Logarithm (Base 10)

The common logarithm uses base 10. It's often used in calculations involving powers of 10, such as pH measurements in chemistry or decibel measurements in acoustics.

Example: To find log₁₀(1000):

1. Press 2ND then LOG.
2. Enter 1000.
3. Press = to get 3.

This is because 10³ = 1000.

Natural Logarithm (Base e)

The natural logarithm uses base e (approximately 2.71828). It's commonly used in calculus, statistics, and physics.

Example: To find ln(e²):

1. Press 2ND then LN.
2. Enter e (press 2ND then e to access the e constant).
3. Press the ^ key (caret) and enter 2.
4. Press = to get 2.

This is because e² is the input, and ln(e²) = 2.

Troubleshooting

Log Function Not Working

If the log function isn't working, try these steps:

• Make sure you're pressing the 2ND key first.
• Check that your calculator is in the correct mode (press MODE to verify).
• Try clearing the calculator memory (press 2ND then DEL).

Incorrect Results

If you're getting unexpected results:

• Double-check your input values.
• Ensure you're using the correct function (log or ln).
• Verify your calculator is in the correct mode (especially for angle units).

Example Calculations

Example 1: Common Logarithm

Calculate log₁₀(100):

1. Press 2ND then LOG.
2. Enter 100.
3. Press = to get 2.

This is because 10² = 100.

Example 2: Natural Logarithm

Calculate ln(√e):

1. Press 2ND then LN.
2. Enter e (press 2ND then e).
3. Press the ^ key and enter 0.5.
4. Press = to get 0.5.

This is because e^0.5 = √e, and ln(√e) = 0.5.