Answers to Exercises in Sign Rules and Bodmas PDF

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Sign Rules and Bodmas Sign rules: + and -

x

÷

3--4→3+4=7 3 - + 4 → 3 - 4 = -1 5+-4→5-4=1 - 13 - - 7 → - 13 + 7 = - 6 - 11 - + 8 → - 11 - 8 = -19

3 x -4 = -12 -3 x 5 = -15 -3 x -6 = 18

32 ÷ -8 = -4 -12 ÷ 3 = -4 -56 ÷ -7 = 8

BODMAS or BIDMAS gives the order in which numerical operations should be done: 1. Brackets 2. Powers Of or Indices 3. Divide Multiply 4. Add Subtract Divide/Multiply can be done in any order, as can Add/Subtract Example: 3 + 4 x 5² ÷ (6 + 4) = 3 + 4 x 5² ÷ 10 = 3 + 4 x 25 ÷ 10 = 3 + 100 ÷ 10 = 3 + 10 = 13 Exercises In questions 11- 18 substitute the values of a, b, c, d and e into the expressions to find the value of y. Remember that 4abc means 4×a×b×c and a means a ÷ b. b Let a = 2, b = -3, c = 4, d = -5 and e = 6. Therefore if y = ab + c then y = 2 × -3 + 4 = -2

1. a) 3 x -5 b) -7 x 9 c) -5 x -4 2. a) 3 - - 8 b) -7 - - 5 c) -7 - + 6 3. a) -35 ÷ 7 b) -32 ÷ -8 c) 108 ÷ -9 4. 3 x 4 + 15 ÷ 3 5. 3 + 7 x 2 6. 3² - 2 x 4 + 18 ÷ 6 7. 4 x ( 3 + 8 ) ÷ 11 + 2 x 9 8. 25 ÷ ( 4² - 11 ) + 3 x 5 9. -24 ÷ -4 + 3 x -6 10. ( 32 - - 8 ) ÷ 4 + 6² ÷ -9

11. y = 3bc + d 12. y = b² - a 13. y = 5a – 2b + de 14. y = √c – (e + 2d) c 15. y = 3a² + d² 16. y = a + bcd – 2e 17. y = 2b – 3c 18. y = 3a b

Answers to Exercises 1. 2. 3. 4. 5. 6. 7. 8. 9.

a) -15 b) -63 c) 20 a) 11 b) -2 c) -13 a) -5 b) 4 c) -12 17 17 4 22 20 -12

10. 6 11. -41 12. 7 13. -14 14. 3 15. 37 16. 50 17. -18 18. -2...