#### Answer

The given function \[f\left( x \right)=7{{x}^{2}}+9{{x}^{4}}\]is a polynomial with degree $4$.

#### Work Step by Step

A function is said to be a polynomial function if
$g\left( x \right)={{a}_{n}}{{x}^{n}}+{{a}_{n-1}}{{x}^{n-1}}+\cdots +{{a}_{2}}{{x}^{2}}+{{a}_{1}}x+{{a}_{0}}$ ,
Where ${{a}_{n}},{{a}_{n-1}},\ldots ,{{a}_{2}},{{a}_{1}},{{a}_{0}}$ are any real numbers with ${{a}_{n}}\ne 0$ and n is any non-negative integer.
Now, the function g(x) is called a polynomial function of degree n; its coefficient is called the leading coefficient.
Now, the given function $f\left( x \right)=7{{x}^{2}}+9{{x}^{4}}$ satisfies all the conditions to be a polynomial; hence, this function is a polynomial and since the highest power of f(x) is 4 then the degree of the polynomial is 4.
Hence, the function $f\left( x \right)=7{{x}^{2}}+9{{x}^{4}}$ is a polynomial with degree 4.