Factorise x^2 +7x +10
First, you need to look at the x2 term and the number 10 - find all the factors of these numbersThe number before x2 is 1, and since 1 is a prime number, the only factor is 1. 1=1x1As for the number 10: 10 = 10x1 and 5x2.Now look at the symbol of the x term. It is a positive number. To make a positive number you must multiply either two positive numbers or two negative numbers.(will need the whiteboard to explain this properly)I use what I call the sausages method to work this out, I will need the whiteboard to explain this:Line up your numbers: When you are first learning you can guess the factors that will multiply to get what you need but over time I have found that students find it easier to see which factors are going to be important. Your AIM is to get to the number +7 - the x term.1 15 2 Cross multiply these terms (1x2=2 and 1x5 = 5). Write result under term.5 2 How can we use the numbers 5 and 2 to get to +7 - simple, 5+2.Therefore, the next part of the sausage comes into play - vertical, which is what the bracket is.(x+5)(x+2)
