Those two factors are a positive 4 and a negative 4 ... and a negative in between. This only works for the difference of squares, not the sum of squares. That's a whole different ball game minus ...

Variation refers to the difference between each dataset ... However, to calculate either of the two metrics, the sum of squares must first be calculated. The variance is the average of the sum ...

Save guides, add subjects and pick up where you left off with your BBC account. Factorise \(x^2 + 7x + 10\). To factorise this expression, find two numbers that have a product of +10 and a sum of +7.