1. Use the FOIL method (x+9)(x+9)
First, outer, inner, last
[tex] x^{2} +9x+9x+81[/tex]
Add your like terms
[tex] x^{2} +18x+81[/tex]
2. When you add or subtract polynomials you add or subtract the like terms and then put them in order from largest to smallest exponents.
3. [tex]-5x(5 x^{3} +10 x^{2} -6x+3)[/tex]
4. Since it is the perimeter, we add the 3 together.
[tex](2 x^{2} +4x-3)+(-3 x^{2} -3)+(5x+19)[/tex]
Add the like terms together:
[tex]2 x^{2} +(-3 x^{2} )=- x^{2} \\ 4x+5x=9x \\ -8+(-3)+19=8[/tex]
Put them in order of exponents
[tex]- x^{2} +9x+8[/tex]
Hope this helps
