We are given the area of a poster board to be:
[tex](x^2+9x-10)in^2[/tex]
The first thing to do is to factorise the expression above, we have:
[tex]\begin{gathered} x^2+9x-10 \\ x^2+10x-x-10 \\ \text{Factorising, we have:} \\ x(x+10)-1(x+10) \\ (x+10)(x-1) \\ \text{These are the factors of the expressions above:} \\ when\colon x=15 \\ \text{The dimensions of the poster board is given by:} \\ x+10,x-1 \\ \Rightarrow15+10,15-1 \\ =25,14 \\ \\ \therefore\text{ the dimensions of the poster board is 25 inches by 14 inches} \end{gathered}[/tex]
Therefore, the dimensions of the post board is 25 inches by 14 inches
