Question

The work of a student to solve the equation 2(3x – 4) = 8 + 2x + 4 is shown below:

Step 1: 2(3x – 4) = 8 + 2x + 4

Step 2: 5x – 6 = 12 + 2x

Step 3: 5x – 2x = 12 + 6

Step 4: 3x = 18

Step 5: x = 6

In which step did the student first make an error and what is the correct step?



Step 2; 6x – 6 = 2(6 + x + 2)
Step 2; 6x – 8 = 12 + 2x
Step 3; 5x – 2x = 12 – 6
Step 3; 5x + 2x = 12 + 6

Answer 1

error in step 2
can you see what it is?

Answer 2

its on left hand side

Answer 3

what do you get when you distribute 2 over (3x - 4)?

Answer 4

2 times 3x + 2 times -4 = ?

Answer 5

what step two is it

Answer 6

to find this all you need is to work out 2 * -4 then check out the 2 step2 answers
2 *-4 = ?

Answer 7

-2

Answer 8

if you are confused by the -4 then multiply 2 by 4 and stick a negative before the answer

Answer 9

not -2

Answer 10

whats 2 times 4 ?

Answer 11

surely you can multiply 4 by 2?

Answer 12

oh thats 8

Answer 13

hello?

Answer 14

right so as its 2 * -4 the result is -8

now check out the options for step 2 and -8

Answer 15

there are two option twos

Answer 16

yes - i know - but which one is correct
look for the -8

Answer 17

so is it the second one in the column?

Answer 18

yes - the second option