Question

Which among the following options is not a polynomial?

• A. $2x^3+4x^3$
• B. $5x^8+8x^5$
• C. $7x^9+9x^{-\frac{7}{8}}$
• D. $6x^4+4x^6$

Answer 1

The correct option is C $7x^9+9x^{-\frac{7}{8}}$

$\underset{–}{Concept}$:
Exponent of a polynomial should be a whole number.

$\underset{–}{Method}$:
$7x^9+9x^{-\frac{7}{8}}$ contains negative power in its 2nd term. Degree is always a whole number.
This expression fails to become a polynomial.

In contrast, every other expression contains whole number exponent in them and therefore passes to become a polynomial except the expression in option 'c'.