Question

Solve by using substitution -5x-y=12 y=-4x-9

Answer 1

Answer:

(-3, 3)

General Formulas and Concepts:

Pre-Algebra

• Order of Operations: BPEMDAS
• Equality Properties

Algebra I

• Solving systems of equations using substitution/elimination

Step-by-step explanation:

Step 1: Define systems

-5x - y = 12

y = -4x - 9

Step 2: Solve for x

Substitution

1. Substitute in y:                              -5x - (-4x - 9) = 12
2. Distribute negative:                      -5x + 4x + 9 = 12
3. Combine like terms:                      -x + 9 = 12
4. Subtract 9 on both sides:             -x = 3
5. Divide -1 on both sides:                x = -3

Step 3: Solve for y

1. Define original equation:                    y = -4x - 9
2. Substitute in x:                                     y = -4(-3) - 9
3. Multiply:                                                y = 12 - 9
4. Subtract:                                               y = 3