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# C2 Edexcel book error? watch

1. dw
2. (Original post by Lunch_Box)
page 74, review exercise 1, question 21

f(x) = x^3 + ax + b

f(4) = 32
f(-2) = -10

answers show a = -12 and b = 16 but i get a = -5, b = -12

working:
1) 4a + b = -32
2) -2a + b = -2
Either there's a typo in the question or the answer.

3. (Original post by Lunch_Box)
page 74, review exercise 1, question 21

f(x) = x^3 + ax + b

f(4) = 32
f(-2) = -10

answers show a = -12 and b = 16 but i get a = -5, b = -12

working:
1) 4a + b = -32
2) -2a + b = -2

4. I got the same answers as you, the book must be wrong. a= -12 and b=16 don't work.

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