Common Errors in Solving 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 can not find an error

• Instead of adding 3k they should subtract 3k

Tags

CCSS.HSA.REI.A.1

Find the Error
What error did the student make when solving the equation:
1/5x + 6 = 3/5x + 5
1x + 6 = 3x + 5
-2x + 6 = 5
-2x = -1
x = 1/2

• The student found an incorrect common denominator

• The student did not multiply all terms by the common denominator

• The student did not use opposite operations appropriately

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

Is the solution below correct?
5d = 2d - 18
-2d   -2d
3d = -18
d = 6

• Yes

• No

Tags

CCSS.8.EE.C.7B

• They combined like terms incorrectly

• They added 14 to both sides instead of subtracting

• They divided incorrectly

• There were no errors made

Tags

CCSS.HSA.REI.A.1

Which is the mistake the student made?

• The student did not distribute properly.

• The student did not combine like terms properly.

• The student did not divide by the proper value.

Tags

8.17

Which step contains an error?

• Step 1

• Step 2

• Step 3

• No Error

Tags

CCSS.HSA.REI.A.1

Which step contains an error?

• Step 1

• Step 2

• Step 3

• No Error

Tags

CCSS.HSA.REI.A.1

Which was the mistake the student made.

• The student did not combine like terms properly on the left side.

• The student did not combine like terms properly on the right side.

• The student divided by the wrong value.

• The student has x on the wrong side of the equal sign.

Tags

8.17

What was the mistake the student make?

• The student did not distribute properly.

• The student did not combine like terms properly.

• The student did not subtract properly.

Tags

8.17

Which step contains an error?

• Step 1

• Step 2

• Step 3

• No Error

Tags

CCSS.HSA.REI.A.1