Factorise X^2 + 13x + 42; from this, please give the answer to X^2 + 13x + 42 = 0
This question aims to look at quadratic equations. We factorise Quadratic equations into two sets of bracketsFirst, we are dealing with X2. X2 is formed from X multipled by X, so each bracket should contain one X --> (X+?) (X+?)The aim here is to find two numbers which add up together to give 13 and Multiply to give a product of 42. Considering the sum of the numbers is not large, this means the numbers themselves are not large too!Thinking about which numbers Multiply to give 42 --> 1 x 42, 2 x 21, 3 x 14, 6 x 7Now look above, which numbers above give a sum of 13? --> 6 & 7!This means (X+6) (X+7) --> X2 + 13x + 42Now if we make this equation equal to 0 --> (X+6) (X+7) = 0; here we get two answers --> X is either -6 or -7We can try putting either one of these numbers in the place of X and find the answer will be equal to 0, Try it out!
