Answer and explanation

Correct answer: C.

  1. Step 1: Multiply matching components and add: .
  2. Step 2: .
Answer
.
Why not the others: is what you get if you multiply the wrong components together. is what you get if you add all components. is what you get if you change the sign of the last product.

Practise more Pure Maths: Coordinate Geometry, Vectors and Counting.

Free questions with an explanation for every one, and full timed GCE Advanced Level (Sri Lanka) mock tests.