Solving System of Equations with Multiplication

Solve the system using Multiplication. 
2x + 3y = 12
5x - y = 13

• x = -3, y = -2

• x = 1.5, y = 2

• x = 6, y = 0

• x = 3, y = 2

Solve for x and y
3x + 2y = 16
7x + y = 19

• (-2,5)

• (-2,-5)

• (2,-5)

• (2,5)

In this system

x+3y=9

4x-2y=-6

it'll be easiest to start by solving the first equation for x.

The result of doing so is x=​9-3y.

Fill in the blanks to plug that expression in and solve for y:

4(​ (a)   )-2​ (b)   =-6

36-​ (c)   y-2y=​ (d)  

36-​ (e)   =-6

• 9-3y

• y

• 12

• -6

• 14y

• x

• 10y

• x+3y

• 24y

In this system

x+3y=9

4x-2y=-6

it'll be easiest to start by solving the first equation for x.

The result of doing so is x=​9-3y.

Fill in the blanks to plug that expression in and solve for y:

4(​9-3y)-2​y =-6

36-​12y-2y=​-6

36-​14y =-6

-14y=​ (a)  

y=​ (b)  

• -42

• 3

• 30

• -3

Find the solution:
2x-5y=15
3x+y=31

• (10,1)

• (13, -8)

• (-10,-7)

• No Solution

−6x + 6y = 0

9x − 8y = 4

• (4, −9)

• Infinite number of solutions

• (−9, 4)

• (4, 4)

Put the steps for solving by ELIMINATION in order:

• Multiply one or both equations by a number to get common but opposite coefficients

• Solve for the remaining variable

• Subtract the equations to eliminate one variable

• Plug that number into either original equation and solve for the other variable

• Make sure the equations are lined up

Consider the system

4x+3y=-1

5x+4y=1

Let's say I want to eliminate the y's. What is the least common multiple of 3 and 4?

LCM = ​ (a)  

Multiply each equation by a number so that the coefficient of y will be 12, with one positive and one negative.

​ (b)   (4x+3y=-1)

​ (c)   (5x+4y=1)

• 12

• 4

• -3

• 3

• 5

• 1

• -1

• -12

Consider the system

4x+3y=-1

5x+4y=1

After we do this multiplication, what will the new equations be?

​ 4(4x+3y=-1) ---> ​ (a)   x +​ (b)   y=​ (c)  

​-3(5x+4y=1)​ ---> ​ (d)   x -​ (e)   y= -3

• 16

• 12

• -4

• -15

• 3

• 5

• 1

• -1

• -12

• -3

Consider the system:

4x+3y=-1

5x+4y=1

Which we converted to:

16 x +​ 12y=​-4

-15x -​ 12y= -3

Combining the equations straight down gives us:

​ (a)   x+​ (b)   y=​ (c)  

Solving for x, we get x=​ (d)  

• 1

• 0

• -7

• 3

• 5

• -1

• -12

• -3