### Home > A2C > Chapter 9 > Lesson 9.1.1 > Problem9-18

9-18.

Which of the following equations are polynomial functions? For each one that is not, justify why not.

1. $y = 3x^{2} + 2x^{2} + x$

1. $y = \left(x − 1\right)^{2}\left(x − 2\right)^{2}$

1. $y = x^{2} + 2 ^{x}$

1. $y = 3x − 1$

1. $y = \left(x − 2\right)^{2} − 1$

1. $y^{2} = \left(x − 2\right)^{2} − 1$

1. $y = \frac { 1 } { x ^ { 2 } } + \frac { 1 } { x } + \frac { 1 } { 2 }$

1. $y = \frac { 1 } { 2 } x + \frac { 1 } { 3 }$

1. $y = x$

1. $y = −7$

The equations in (c), (f), and (g) are not polynomials. Refer to the Math Notes box for this lesson if you are confused.