1. ## Polynomial or not

y= (√x) + x^5 - 7x^6

y= 3ix³ + 9

My textbook says they are not polynomial functions. Why?

Thanks for helping!

2. "A polynomial is an expression of finite length constructed from variables and constants, using only the operations of addition, subtraction, multiplication, and non-negative, whole-number exponents" - Wikipedia

Can you see what make them not a polynomial by using the description above?

3. yeah, but both equations have positive whole integer exponents. I don't see how they aren't polynomial functions.

My guess is the "√x" in the first equation and the "3ix³" in the second equation. If so, can someone explain why they make the equations not polynomial functions?

Thanks.

4. √x = x^(0.5)
("non-negative, whole-number exponents")
This has a decimal exponent therefore it is not a polynomial.

In the second one, 3ix³ has a imaginary number in it, therefore that part will not be graphed on the simple cartesian plane, leaving only the y=9 part to be graphed.