Factorise fully X^2 - 6X + 8

Factorising means reducing an equation to a set of brackets, in the form (x+a)(x+b), where a and b are constants. To factorise this equation, we must find two numbers that add to make -6, and multiply to make 8. An easy way to approach this is to list the factors of 8 in pairs, and see which pair adds to make -6. The pairs are (8,1) and (2,4), but when we add these, we cannot make -6. Both answers are positive. At this point, we can recall that the multiplication of two negative numbers is equal to a positive answer, so we can test the negative pairs of factors that still multiply to 8. These are (-1, -8) and (-2, -4). Now, we can see that whilst -1 + -8 = -9, -2 + -4= -6. Therefore, the pair of number in the brackets is (-2,-4), since these add to make -6 and multiply to make 8. Filling in the blanks of the original equation, we are left with (x-2)(x-4).

Answered by Dan D. Maths tutor

2574 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

If we take a fair 6 sided die and colour 3 of the faces blue, 2 green and 1 red and then roll the die 300 times, work out and estimate the number of times it will land with the green side up.


Make r the subject of the formula x = (3r - 4)/5


Draw the graph of y=2-3x for values of x from -3 to 3.


A house is bought for £150,000 at the start of 2005. For 3 years it loses 10% of its original value per year. After this time it loses 10% per year. What was its value at the end of 2011/start of 2012?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo
Cookie Preferences