Which expression is a polynomial in (x) of degree (4)?

Correct answer: \(x^4-2x+6\)

In \(x^4-2x+6\), the highest power of \(x\) is \(4\), and all exponents of \(x\) are non-negative integers. Therefore, it is a polynomial in \(x\) of degree \(4\). \(x^3+4\) is a polynomial, but its degree is \(3\). In \(\frac{1}{x}\) and \(\sqrt{x}\), the exponents of \(x\) are \(-1\) and \(\frac12\), so they are not polynomials. Exam tip: exponents of a variable in a polynomial can only be \(0,1,2,\ldots\).