The cubic polynomial 6x3+kx2+25x−126x^3 + kx^2 + 25x - 126x3+kx2+25x−12 is denoted by f(x)f(x)f(x), where k k\,k is a constant.
It is given that (2x+3)(2x + 3)(2x+3) is a factor of f(x)f(x)f(x).
Use the factor theorem to show that k=31k = 31k=31.
Using this value of kkk, factorise f(x)f(x)f(x) completely.
302 exam-style questions on WJEC A Level Maths 1.2 Algebra and Functions, covering 1.2.1 Algebra and Functions, 1.2.2 Algebra and Functions, 1.2.3 Algebra and Functions, 1.2.4 Algebra and Functions, 1.2.5 Algebra and Functions, 1.2.6 Algebra and Functions, 1.2.7 Algebra and Functions, 1.2.8 Algebra and Functions, 1.2.9 Algebra and Functions, 1.2.10 Algebra and Functions, 1.2.11 Algebra and Functions, and 1.2.12 Algebra and Functions. Each one has a worked solution and a mark scheme showing where the marks go.