In this week’s blog one of our leading examiners, Patricia, takes you through how to avoid this common algebra mistake from GCSE Maths Exams that most students made. We are looking at an advanced algebra question involving indices from June 2014 Higher Non Calculator Paper 1. Patricia, has told us that this was a question that MANY students made a simple but common error on. The good news? It’s easily fixable… when you know what you’re looking for!
One of the great things about SchoolOnline is that we work with some of the nation’s top examiners to identify the most common errors students have made in past GCSE Maths exams. That way, we can help you avoid them! It’s all part of our Smarter Learning, Better Grades process.
Here’s what it was and how you can avoid making the same error.
The GCSE Maths algebra question that many students made a mistake on:
Simplify (3x²y⁴)³
(2 Marks)
The answer:
So what was the common algebra mistake?
Patricia says that the first thing to do is take your time on answering questions like this, as not reading them properly can lead you to make simple errors. She also recommends keeping a highlighter to hand and underlining the key command word in a question. In this example it is ‘simplify’.
This common Algebra Mistake from GCSE Maths Exams was a Grade A (Grade 7) level question, making it one of the most challenging questions on the paper.
In answering Simplify (3x²y⁴)³ one should start by writing it out as Patricia has done in the image below:
The mistake many students made was to add the 3 in each bracket, confusing the number with the indices. However, as Patricia highlights, you need to multiply the 3s. 3 x 3 x 3 = 27.
This is where many students go wrong – putting 9 instead of 27. You must remember that you are multiplying your numbers, NOT adding them.
The next step is to simplify the indices. These you do need to do addition on. Therefore x²+ x² + x² = x⁶.
You then do the same with the y term. So y⁴ + y⁴ + y⁴ = y¹²
Therefore, the answer is 27x⁶ y¹²
If you’d like to practice further challenging indices questions why not sign up to our 3 Day Free Trial. You’ll get full access to all of our expert SchoolOnline Maths tutorial videos, many of which cover the common mistakes from GCSE Maths Exams. Just head to the Algebra topic and the Powers and Roots subtopic once you’ve signed up to practice advanced algebra questions like this.
