Answer:
(a + b)(c + d), ac+ ad+ bc + bd, 2x squared + x - 3 or (2x+ 3)(x -1).
Explanation:
For an expression of the form (a + b)(c + d), the expanded version is ac + ad + bc + bd, in other words everything in the first bracket should be multiplied by everything in the second. Factorising is the reverse of expanding brackets, so it is, for example, putting 2x² + x - 3 into the form (2x + 3)(x - 1).