How do I factorise x^2 - 4?
This is similar to other factorisation problems such as x2 + 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 x2 + 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 = x2 - 4.
