Question

Using the Identities, simplify the following

$(x-5)(x+1)$

Answer 1

Step 1 : We need to identify the identity first, the question is in the form of $(x+a)(x+b)$ which is equal to $x^2+(a+b)x+ab$

so if we compare the question with the identity we get $a=-5andb=1$

Step 2 : Applying the formula

$$\begin{gathered} (x-5)(x+1)=x^2+(-5+1)x+(-5\times 1) \\ =x^2-4x-5 \end{gathered}$$

Hence the solution is $x^2-4x-5$