(5x^3-3x^4-2x-9x^2-2)+(3x^3+2x^2-5x -7)

-3x⁴ + 8x³ - 9x² - 7x - 9

General Formulas and Concepts:

Step-by-step explanation:

Step 1: Define expression

(5x³ - 3x⁴ - 2x - 9x² - 2) + (3x³ + 2x² - 5x - 7)

Step 2: Simplify

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18