Question 7 of 17intermediate🔍 AnalyzeShort Answer9 marks

Observe each of them and identify if there is a mistake. If you think there is a mistake, try to explain what might have gone wrong. Then, correct it and give the value of the expression. 1. If a = -4, then 10 - a = 6. 2. If d = 6, then 3d = 36. 3. If s = 7, then 3s - 2 = 15. 4. If r = 8, then 2r + 1 = 29. 5. If j = 5, then 2j = 10. 6. If m = -6, then 3(m + 1) = 19. 7. If f = 3, g = 1, then 2f - 2g = 2. 8. If t = 4, b = 3, then 2t + b = 24. 9. If h = 5, n = 6, then h - (3 - n) = 4.

(1)
Answer

False. 10 - (-4) = 10 + 4 = 14.

(2)
Answer

False. 3d = 3×63 \times 6 = 18.

(3)
Answer

False. 3s - 2 = 3×73 \times 7 - 2 = 21 - 2 = 19.

(4)
Answer

False. 2r + 1 = 2×82 \times 8 + 1 = 16 + 1 = 17.

(5)
Answer

True. 2j = 2×52 \times 5 = 10.

(6)
Answer

False. 3(m + 1) = 3 × (-6 + 1) = 3 × (-5) = -15.

(7)
Answer

False. 2f - 2g = 2×32 \times 3 - 2×12 \times 1 = 6 - 2 = 4.

(8)
Answer

False. 2t + b = 2×42 \times 4 + 3 = 8 + 3 = 11.

(9)
Answer

False. h - (3 - n) = 5 - (3 - 6) = 5 - (-3) = 5 + 3 = 8.

Explanation

(1) The mistake is not handling the negative sign correctly. Subtracting a negative number is equivalent to adding its positive. (2) The mistake is treating 3d as 3d3^{d} or d3d^{3} instead of 3 × d. (3) The mistake is calculating 3×73 \times 7 = 17 instead of 21. (4) The mistake is calculating 2×82 \times 8 = 28 instead of 16. (5) This is correct. (6) The mistake is in evaluating m + 1 = -6 + 1 = -5, not 5. (7) The calculation gives 4, not 2. (8) The mistake is treating 2t + b as 2tb or some other operation. (9) The mistake is in evaluating 3 - 6 = -3 and then subtracting a negative.

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