01 Which expression is a polynomial but not a cubic polynomial?
Answer and explanation
Correct answer: B. \(5x^4-x+6\)
Explanation: In \(5x^4-x+6\), the highest power of \(x\) is \(4\). Therefore, it is a fourth-degree polynomial, not a cubic polynomial. \(2x^3+x+1\) is cubic because its highest power is \(3\). In \(\sqrt{x}+x^3\), \(\sqrt{x}=x^{1/2}\), while \(x^{-3}+x^2\) contains a negative exponent, so neither is a polynomial. Exam tip: the exponents of a variable in a polynomial must be \(0\) or positive integers.