8. Algebra


9. A box contains 150 coins, all €1 or €2 coins. The total value of the coins is €204. How many of each coin are in the box? __________________________________ ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________


10. Solve for x, y, and z:


x + 2y + z = 1 2x – y – z = 2 – 3x –2y + z = 5


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11. Can these three simultaneous equations be solved, and why? x + 2y + z = 1


2x + 4y + 2z = 2 –x –2y – z = –1


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12. Solve for a, b and c


2a + b – c = 3 a – b + 2c = 7


–3a + b –2c = –11


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If a = b then a2


Hint for Project 8·1: the flaw is in the last step! = ab, then a2


- ab = 0. Dividing by 0 is not allowed in maths. 87


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