DO NOT USE A CALCULATOR IN THIS QUESTION. The polynomial `p(x) = 10x³ + ax² -10x+b`, where a and b are integers, is divisible by `2x+1`. When `p(x)` is divided by `x+1`, the remainder is -24.
- (a)Find the value of a and of b.[4]
- (b)Find an expression for p(x) as the product of three linear factors.[4]
- (c)Write down the remainder when p(x) is divided by x.[1]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.
- [M1] For use of the factor theorem
- [M1] For use of the remainder theorem
- [M1 Dep] on both previous M marks for solution of their equations without using a calculator
- [A1] a = -27, b = 3
- [M1] Allow for observation or algebraic long division. Their a and b must be integers.
- [A1] (2x+1)(5x²-16x+3)
- [M1] for attempt to factorise their 3-term quadratic
- [A1] all correct from fully correct working
- [B1] FT on their (integer) b
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