Find the Error in Two Step 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

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 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

Consider the problem

-4(6 - y) + 4 = -4

Identify the first step that is incorrect.

Tags

CCSS.HSA.REI.A.1

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

Find the Error
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

Tags

CCSS.HSA.REI.A.1

Did Sarah make an error? If so, which is the best description of her error?

• She didn't distribute correctly. The second step should read 3x - 12 = 24

• She didn't distribute correctly. The second step should read -3x - 12 = 24

• She didn't distribute correctly. The second step should read -3x + 12 = 24

• She didn't make an error.

Tags

CCSS.HSA.REI.A.1

4x - 3 = -2x + 4
6x - 3 = 4
6x = 7
x = 7/6

• There is no error

• They should have subtracted 2x

• They should have subtracted 3

• it should be 6/7

Tags

CCSS.HSA.REI.A.1