Question

Practice1. Solve each equation.a. 0 = x2 – 7x – 18

Answer 1

Notice that:

$\begin{gathered} -18=(-9)\cdot2, \\ -9+2=-7. \end{gathered}$

Therefore:

$(x-9)(x+2)=x^2-7x-18.$

If x²-7x-18=0 then:

$\begin{gathered} x-9=0\text{ or x+2=0,} \\ x=9\text{ or x=-2.} \end{gathered}$

Answer: x=9 or x= -2.