Answer: [tex]15r^2-21r+5[/tex]
Step-by-step explanation:
Given: Perimeter of triangular garden = [tex]25r^2 - 9r + 14[/tex]
The sum of two sides of the garden = [tex]10r^2 + 12r + 9[/tex]
Perimeter is the sum of all sides of a triangle.
Third side = Perimeter of triangular garden - sum of two sides of the garden
[tex]=25r ^ 2 - 9r + 14-(10r ^ 2 + 12r + 9)\\\\=25r ^ 2 - 9r + 14-10r ^ 2 - 12r - 9\\\\=15r^2-21r+5[/tex]
The expression represent the third side = [tex]15r^2-21r+5[/tex].
