How do I factorise x^2 ​- 4?

This is similar to other factorisation problems such as x+ 5x - 6. In this problem, you would find prime factors of -6 that add up to 5 (In this case -3, -2). 
Now, do the exact same with this problem! This is the same as x+ 0x - 4, so you need to find factors of -4 that add up to 0. In this case these two primes will be -2 and 2. Using these factors, you can reach the answer: (x - 2)*(x + 2).
To check your work, multiply (x - 2)(x + 2) to get x2 + 2x - 2x - 4 = x- 4.

Answered by Lauren G. Maths tutor

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