Answer:
5. D
6. A
7. A
Step-by-step explanation:
5. Perimeter= 2 (length+breadth)
Length=
[tex]x {}^{2} + 7x - 9 [/tex]
Breadth=
[tex]x {}^{2} - 2x[/tex]
[tex]2((x {}^{2} + 7x - 9) + (3x {}^{2} - 2x)) \\ 2x {}^{2} + 14x - 18 + 6x {}^{2} - 4x \\ 2x {}^{2} + 6x {}^{2} + 14x - 4x + - 18 \\ 8x {}^{2} + 10x - 18[/tex]
6. Perimeter=
[tex](7x {}^{2} - 12)+(-5x + 30)+(3x {}^{2}+4x) [/tex]
[tex]7x {}^{2} - 12 - 5x + 30 +3x {}^{2} + 4x \\ 7x {}^{2} + 3x {}^{2} - 5x - 4x -12 + 30 \\ 10x {}^{2} - x + 18[/tex]
7. 2(x^2+3x-5)-3(2x^2-7x+8)
2x^2+6x-10-6x^2+21x-24
2x^2-6x^2+6x+21x-10-24
-4x^2+27x-34
