Which of the following statements identifies the error the student made?

[eddy2017]

DIRECTIONS: Read the question and select the best response.
In solving the linear equation 5x −9 = 3x + 3, a student wrote 5x + 3x − 9 = 3x − 3x + 3 as the next step. Which of the following statements identifies the error the student made?

Choose an answer
a. The student added and subtracted the same amount on both sides of the equation.?
b. The student multiplied the same amount on both sides of the equation.
c. The student subtracted the same amount on both sides of the equation.
d. The student added the same amount on both sides of the equation.
I will simplify the expression and try to see what the student does wrong because I am not seeing it right away.
5x −9 = 3x + 3
5x-9+9=3x+3+ 9
5x=3x+12
5x-3x=3x-3x+12
2x=12
2x/2=12/2
x=6

well, d is out of the question because s/he did not do that.
I am disregarding c too. they do not add 3x but to the left hand side.
I will go for choice a. they added 3x to the left hand side and subtracted it from the right hand side, yes, I am going for this one.

thanks for any rectification or approval
eddy

 

[lev888]

DIRECTIONS: Read the question and select the best response.
In solving the linear equation 5x −9 = 3x + 3, a student wrote 5x + 3x − 9 = 3x − 3x + 3 as the next step. Which of the following statements identifies the error the student made?

Choose an answer
a. The student added and subtracted the same amount on both sides of the equation.?
b. The student multiplied the same amount on both sides of the equation.
c. The student subtracted the same amount on both sides of the equation.
d. The student added the same amount on both sides of the equation.
I will simplify the expression and try to see what the student does wrong because I am not seeing it right away.
5x −9 = 3x + 3
5x-9+9=3x+3+ 9
5x=3x+12
5x-3x=3x-3x+12
2x=12
2x/2=12/2
x=6

well, d is out of the question because s/he did not do that.
I am disregarding c too. they do not add 3x but to the left hand side.
I will go for choice a. they added 3x to the left hand side and subtracted it from the right hand side, yes, I am going for this one.

thanks for any rectification or approval
eddy

You don't need to simplify or do any calculations. The only thing you need to do is compare the 2 equations and find differences - similar to finding differences in pictures for kids.

 

[eddy2017]

You don't need to simplify or do any calculations. The only thing you need to do is compare the 2 equations and find differences - similar to finding differences in pictures for kids.

thank you. that was easy when I set it up one against the other. wow. t hank you, lev

1. The student added and subtracted the same amount on both sides of the equation =choice a