Solving Linear Equations

Find the error in the problem below:

19 - 2k = 3k - 1

+3k +3k

19 + 1k = -1

-19 -19

k = -20

• They should have divided by 1 for the last step

• They should add 19 instead of subtracting 19

• I cannot find an error

• Instead of adding 3k they should subtract 3k

What error did the student make when solving the equation:

5x + 6 = 66

5x - 6 = 66 -6

5x = 60

(5)5x = 60(5)

x = 300

• The student subtracted 6 from both sides instead of adding

• Student multiplied by 5 instead of dividing by 5

• Student got the wrong answer when subtracting 66-6

• The student did not correctly eliminate the variable from one side of the equation

-(n - 8) = -2

• 6
• 10
• -10
• -6

Tags

CCSS.7.EE.B.4A

-8(-8x - 6) = -6x - 22

• 2/5
• -1
• 8/7 
• 2

Tags

CCSS.8.EE.C.7B

2x - 3 + 4x = 27

• 12
• 4
• 5
• 15

Tags

CCSS.8.EE.C.7B

What is the first step in solving the equation 2a - 4(a - 5) = 10

• Add 4 to both sides
• Add the 2a and a 
• Distribute 4 to a and -5
• Distribute -4 to a and -5

Tags

CCSS.8.EE.C.7B

Determine if (4, 1) is a solution for the system of equations. Hint: Plug in 4 for x, and 1 for y.

y = -x + 5

y = 2x - 7

• Yes

• No

A system of linear equations is...

• Math Magic

• One Equation

• Always more than two equations

• A set of two or more equations

What is the solution?

• (1, -1)
• (-1, 1)
• (0, -2)
• (0, 1)

Tags

CCSS.8.EE.C.8A

How can you tell if a point is a solution to a linear system?

• It makes the first equation true.

• The (x,y) coordinates satisfy both equations

• It makes logical sense

• It makes neither equation negative

• The ordered pair (x, y) is a point on both lines