# THE Exponential Function - How to Revise

Updated: Sep 25

- What is the most common, yet under-appreciated topic on the Leaving Cert HL exam paper?

- What was the **WORST ANSWERED QUESTION** in Paper 1 of LCHL 2022? (watch the video in Tip #5 to find out)

THE Exponential function is one of the more fascinating concepts on the Leaving Cert course.

Interestingly, most text books don't put a huge emphasis on it.

But when you look at how often it appears in the LC, there's a case that it deserves its own chapter (see Tip #4)

*Tacit Maths Module on the Exponential Function (FREE)*

The Exponential Module/Worksheets/Solutions are FREE to everyone!

Link**: **__https://www.tacitmaths.ie/theexponentialfunction__

This worksheet/module is designed to be quite short.

**The aim should be to target exam questions ASAP.**

The module contains:

- Notes with corresponding eLearning module.

- 10 LCHL Exam questions

- Powerpoint solutions to all of the above.

**Tips for Revising The Exponential Function**

**1. Exponentials V THE Exponential**

Worksheet: Page 3 - 4

Powerpoint: Page 9 -18

This is an important distinction to make.

"Exponential Equations" are any equation where the unknown is a power.

Well prepared students will know that we use Logs to solve equations.

However, THE Exponential function is a special type of function.

It is critical that students understand the differences and similarities as to how you approach both of these.

**2. Trouble with Decimals**

Worksheet: Page 4

Powerpoint: Page 20

For some reason, many students get completely turned off when they see equations/functions with decimals in them.

A well prepared student should be fully confident in working with integers, decimals, fractions, standard notation, percentages etc.

The exercise above should help with that.

NOTE: Students should note that all the solutions to the above exercise are whole numbers...

**3. Incomplete Functions**

Worksheet: Page 5 - 6

Powerpoint: Page 9 -18

A complete function should only have one variable in it (usually x)

When you look at the Part B questions, you will find that a very common feature is they have two extra unknowns (see image).

The approach to solving this problem is quite straightforward as you will see.

**HINT:** One of the clues that will help is finding the "initial value".

It is almost always mentioned in some shape or form.

**4. Appearances in Previous Leaving Certs**

- LC 2023: 30 Mark Questions (*with Differentiation*)

- LC 2022: 50 Mark question

### - LC 2022: 30 Mark question *(with Sequences & Series)*

### - LC 2021: 50 Mark question *(Calculus)*

### - LC 2020: 55 Mark question *(Calculus)*

### - LC 2019: 25 Mark question *(Algebra/Calculus)*

### - LC 2018 Q7: 50 Mark Question

### - LC 2018 Q8: 50 Mark Questions

### - LC 2017: 55 Mark Question *(Calculus)*

### - LC 2016: 25 Mark Question *(Functions/Algebra)*

### - LC 2014: 60 Mark Question* (Calculus)*

**5. WORST Answered Question in Leaving Cert Paper 1**

In 2022, students had the option of skipping some Part A questions.

The VAST MAJORITY skipped Q4, and those who attempted it did quite poorly!

**TIP: **Rather than simply watching the video below, why not TRY IT OUT YOURSELF FIRST.

See how you would have done and compare your solution to the video.

(Click to Download)

**Video Solution:**

For more information on how to sign up to the modules on Tacit Maths, visit our website __(www.TacitMaths.ie)__ or contact Diarmuid directly at: diarmuid@tacitlearning.com