Question

Which line shows the first error in the solution?

Answer 1

http://lv.k12.com/mediaFiles/Ninth_Grade/Math/Unit15164/Lesson64989/05_06_LQ_01.gif

Answer 2

please help!

Answer 3

How do you go from line 1 to line 2?

Answer 4

?

Answer 5

This is line 1: 5(x - 5) = 15
This is line 2: 5x - 25 = 15
Is line 2 correct? What was done to line 1 to get line 2?

Answer 6

it was multiplied?

Answer 7

Yes, the left side was multiplied out.
5(x - 5) in line 1 became 5x - 25 in line 2
That is the correct way of distributing the 5, so line 2 is correct.

Answer 8

Now let's look at line 2 again and compare it to line 3.

Answer 9

the 5 dissapeared

Answer 10

This is line 2: 5x - 25 = 15
This is line 3: 5x - 25 = 15 - 25
What changed from line 2 to line 3?

Answer 11

wait 15 was substracted from both sides

Answer 12

No. There is a 15 in line 2 already. It's still there in line 3.
What difference do you see between line 2 and line 3?

Answer 13

i dont know

Answer 14

25 is bigger than 15

Answer 15

The difference between line 2 and line 3 is that in line 3, an additional 25 is being subtracted from the right side. Notice what is in red in line 3 below.
This is line 2: \(5x - 25 = 15 \)
This is line 3: \(5x - 25 = 15 \color{red}{- 25}\)

Answer 16

oh...

Answer 17

so line 3 is wrong

Answer 18

Do you agree that the only difference there is in line 3 compared to line 2 is that in line 3 there is a 25 being subtracted from the right side?

Answer 19

yes...

Answer 20

Yes, you are correct.
You can't subtract a number from just one side of an equation.
You must do the same to both sides.
Line 3 is the first mistake in the solution of this equation.

Answer 21

Good job!

Answer 22

thanks so much, can u help with another one!

Answer 23

ok, just one more.
pls start a new post. i'll be there soon.

Answer 24

k