Explanation
Definition of a Quadratic Polynomial:
For an algebraic expression to be a quadratic polynomial, it must satisfy two core criteria:
It must be a polynomial (the exponents of all variables must be non-negative integers).
The degree of the polynomial (the highest exponent of the variable x) must be exactly 2.
Let's evaluate each option systematically:
Option (a): x2−3x+4
Simplifying the first term: x2=x (for x≥0).
The expression simplifies to x−3x+4=−2x+4.
The highest exponent here is 1. This is a linear polynomial, not quadratic.
Option (b): x+5
Rewriting the radical term gives x21+5.
Since the exponent 21 is a fraction (not an integer), this expression is not a polynomial at all.
Option (c): x3+2x
Option (d): x2+5−3
The exponent of the variable x is 2, which is a non-negative integer.
The square roots are only on the constant numerical values (5 and 3), which is completely valid.
Since the maximum power of x is 2, its degree is 2.
Result: This is a quadratic polynomial.
Correct Answer
The correct option is (d) x2+5−3.