Question 1 10 marks
Let \(p(x)=x^3+kx^2+x+6\). Given that \(x-2\) is a factor of \(p(x)\):
- Use the Factor Theorem to find \(k\). 2
- Factorise \(p(x)\) fully. 3
- Solve \(p(x)=0\). 3
- Find the remainder when \(p(x)\) is divided by \(x+2\). 2
Work without notes. This compact test checks the full route: factor condition, factorisation, all roots, then a non-monic remainder.
Total: 12 marks. Work on paper first, then reveal the marking guide below.
Let \(p(x)=x^3+kx^2+x+6\). Given that \(x-2\) is a factor of \(p(x)\):
Find the remainder when \(q(x)=3x^3+5x^2-x+1\) is divided by \(2x-1\).
(a) \(x-2\) factor means \(p(2)=0\).
(b) \(p(x)=x^3-4x^2+x+6\).
(c) \((x-2)(x-3)(x+1)=0\).
(d) For \(x+2\), substitute \(x=-2\):
Remainder = \(-20\).
\(2x-1=0\Rightarrow x=\frac12\).
Remainder = \(\frac{17}{8}\).
Use the score to choose a specific repair action, not just a vague plan to revise.
This test is original. Use these sources for scope and additional textbook work.
Grade 12 Polynomials: cubic factorisation and theorem application through degree 3.
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