Substitution

When using substitution to solve this system of equations, what is the result of the first step?

y = -10x + 2

-x + 10y = 3

• -x + 10(-10x + 2) = 3

• -10x + 2 + 10y = 3

• -x + 10y(-10x + 2) = 3

• -x – 10x + 2 + 10y = 3

When using substitution to solve this system of equations, what is the result of the first step?

y = –4 + 6x

-3x + 4y = 6

• -3x + 4(-4 + 6x) = 6

• -3x + 4(4 – 6x) = 6

• -3(-4 + 6x) + 4y = 6

• -3(4 – 6x) + 4y = 6

When using substitution to solve this system of equations, what is the result of the first step?

y = 4 – 5x

7x – y = 0

• 7x – 4 – 5x = 0

• 7(4 – 5x) – y = 0

• 7x – (4 – 5x) = 0

• 7x – y(4 – 5x) = 0

The following system of equations was solved by using the substitution method. In which step did an error first occur?

y = 9x – 7

2x – y = 14

2x – (9x – 7) = 14 Step 1

2x – 9x – 7 = 14 Step 2

-7x – 7 = 14 Step 3

-7x = 21 Step 4

x = -3 Step 5

• Step 1

• Step 2

• Step 3

• No mistake

The following system of equations was solved by using the substitution method. In which step did an error first occur?

5y – 5x = – 50

x – 3y = 20

5y – 5(3y + 20) = -50 Step 1

5y – 15y – 100 = -50 Step 2

-10y – 100 = -50 Step 3

-10y = -150 Step 4

x = 15 Step 5

• Step 1

• Step 2

• Step 3

• Step 4