### Chap 6 Error Analysis Homework 2 Ex 6.2 Q1(f)

Go through the working and attempt to identify where the error is.

1. Should be 20+8x not 20-8x

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3. He forgot that -4*-2x should be +8x, not -8x.

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6. On Line 2, the third sign should be + and not -

1. It is supposed to be 9x-3-20+8x=-10

7. he should change the negative signs to positive sign at -8x
9x-3-20-8x=-10

8. There is a mistake at Line 2. -4*-2x = 8x not -8x!

9. The second line. It should be +8x as -4 x -2x is +8x

10. When a negative number is multiplied by another negative number, the answer will be a positive number. When negative 2x is multiplied by negative 4, the answer should be positive 8x and not negative 8x.

11. The sign on line 2 should be + and not -

12. In line two:it should be 20+8x as negative and negative equals positive.

13. The -8x on line 2 should be +8x as negative times negative is positive.

14. On the second line of this equation,it should be a positive sign instead of a negative one.As -4 times -2x,20-8x should be 20+8x.

15. The -8x should be +8x.

16. the error is expanding from line 1 to 2, the error is -4(5-2x)=-20-8x. the correct way is -4(5-2x)=-20+8x

17. In line 2, it should be +8x , not -8x. Hence therefore, line 3 should be 17x - 23 = -10 . Line 4 should be 17x = 23 - 10 . Line 5 should be x = 13/17 .

18. Line 1: N/A
Line 2: 20-8x should be 20+8x. When a negative sign and another negative sign is multiplied together, the product is a positive one.
Line 3:N/A
Line 4:N/A
Line 5:N/A

19. The second line, He got muddled up. -4 x -2x is 8x as a negative times a negative is a positive.
so 17x -23= -10
17x=-10+23
17x=33
so x= 1 6/7

20. The second line should be 20+8x not 20-8x

21. The working should be as follows:
3(3x-1) - 4(5-2x) = -10

After Factorisation, the answer will be:
9x-3-20+8x = -10

Now we move all the common terams together.
9x+8x-3-20 = -10
9x+8x = -10+3+20
17x = 13
x = 17/13
= 1/4/13

22. On Line 2, the '-' in 20 - 8x should be a '+'.
So, it should be like this:
Line 2: 9x -3 - 20 + 8x = -10
Line 3: 17x -23 = -10
Line 4: 17x = -10 + -23
Line 5: x = -10 + -23/ 17

1. Line 4: 17x = -33
Line 5: x = -33/17