Question:
Which of the following expressions are polynomials in one variable and which are not?
State the reasons for your answers
1. $3 x^{2}-4 x+15$
2. $y^{2}+2 \sqrt{3}$
3. $3 \sqrt{x}+\sqrt{2} x$
4. $x-4 / x$
5. $x^{12}+y^{2}+t^{50}$
Solution:
1. $3 x^{2}-4 x+15$ it is a polynomial of $x$
2. $y^{2}+2 \sqrt{3}$ it is a polynomial of $y$
$3 \sqrt{x}+\sqrt{2} x$ it is not a polynomial since the exponent of $3 \sqrt{x}$ is not a positive term
4. $x-4 / x$ - it is not a polynomial since the exponent of $-4 / x$ is not a positive term
5. $x^{12}+y^{2}+t^{50}$ it is a three variable polynomial which variables of $x, y, t$