01 Which of the following is a polynomial in (x)?
Answer and explanation
Correct answer: B. (3x^2-5x+1)
Explanation: In a polynomial, powers of the variable must be whole numbers including zero. In (3x^2-5x+1), the powers are (2), (1), and (0).
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SubjectsMathematics
बहुपद की परिभाषा
In Class 9 Mathematics, under Introduction to Polynomials, Definition of a Polynomial explains expressions in which variables have only non-negative integer powers. Students learn to distinguish polynomials from expressions containing negative, fractional, or other invalid exponents, identify constant and zero polynomials, and recognise polynomials by their highest power and basic type.
Correct answer: B. (3x^2-5x+1)
Explanation: In a polynomial, powers of the variable must be whole numbers including zero. In (3x^2-5x+1), the powers are (2), (1), and (0).
Correct answer: C. (\frac{5}{x}+1)
Explanation: The direct answer is option C: \(\frac{5}{x}+1\) is not a polynomial in \(x\). A polynomial is made from constants and non-negative integral powers of the variable, such as \(x^0,x^1,x^2\), combined by addition, subtraction, and multiplication. In \(5/x\), the variable is in the denominator, so \(5/x=5x^{-1}\); the exponent is negative, which is not allowed in a polynomial. Option A, \(x^2+3x\), is a polynomial because its powers are 2 and 1. Option B, \(7x-4\), is a polynomial because it has powers 1 and 0. Option C fails because of the negative power. Option D, 9, is a constant polynomial; it can be viewed as \(9x^0\). Do not be confused by the way the options are printed: the mathematical expressions being tested are the displayed expressions themselves. Memory cue: variable in a denominator usually means “not a polynomial.”
Correct answer: C. Non-negative integers including zero
Explanation: In a polynomial, powers can be like (0,1,2,3). Fractional or negative powers do not fit the definition of a polynomial.
Correct answer: C. 3
Explanation: In \(4x^3-2x+8\), the powers of \(x\) are 3, 1, and 0 respectively. Therefore, the highest power is 3. The number 8 is a constant term, whose power is taken as 0, so it is not the highest power. Exam tip: To find the degree of a polynomial, identify the greatest power of its variable.
Correct answer: A. Linear polynomial
Explanation: In \(6x+11\), the highest power of \(x\) is \(1\), so its degree is 1. A polynomial of degree 1 is called a linear polynomial. A quadratic polynomial has highest power 2, so it is not correct here. Exam tip: To identify the type of a polynomial, look for the greatest exponent of the variable.
Correct answer: B. Quadratic polynomial
Explanation: The degree of a polynomial is the highest power of its variable with a non-zero coefficient. In \(5x^2+2x-3\), the highest power of \(x\) is 2, so it is a quadratic polynomial. A linear polynomial has degree 1, while a constant polynomial has no variable. Exam tip: To identify the type of a polynomial, first find the highest power of the variable.
Correct answer: C. Cubic polynomial
Explanation: The degree of a polynomial is the greatest power of its variable with a non-zero coefficient. Here, the powers of the terms are 3, 2, and 0, so the highest power is 3. Therefore, it is a cubic polynomial. A quadratic polynomial has degree 2, so option B is not correct. Exam tip: To identify the type of a polynomial, first find the highest power of the variable.
Correct answer: D. Constant polynomial
Explanation: (12) has no variable, so it is a constant polynomial. A non-zero constant polynomial has degree (0).
Correct answer: A. Yes, it is the zero polynomial.
Explanation: Yes, 0 is called the zero polynomial, so it is a polynomial. A polynomial need not contain a variable; constant polynomials such as 5 and 0 are also polynomials. The degree of the zero polynomial is not defined, so option D is incorrect. Exam tip: A polynomial with constant term only 0 is called the zero polynomial.
Correct answer: B. बहुपद में चर का घात ऋणात्मक नहीं हो सकता।
Explanation: In a polynomial, exponents of variables must be non-negative integers such as 0, 1, or 2. Here, \(x^{-1}=1/x\), so the variable occurs in the denominator and the expression is not a polynomial. Exam tip: reject expressions with negative or fractional variable exponents.
Correct answer: B. \(x^2+4x+4\)
Explanation: In \(x^2+4x+4\), the powers of \(x\) are \(2\), \(1\), and \(0\). All are non-negative integers, so it is a polynomial in \(x\). \(\sqrt{x}=x^{1/2}\) has a fractional exponent, while \(\frac{2}{x}=2x^{-1}\) and \(x^{-1}+5\) contain negative exponents; therefore, they are not polynomials. Exam tip: variable exponents in a polynomial can only be \(0,1,2,\ldots\).
Correct answer: B. Because it has a fractional power
Explanation: A polynomial in x is built from terms whose powers of x are non-negative whole numbers such as 0, 1, 2, or 3. A constant term is allowed, addition is allowed, and the number 3 itself causes no problem. The expression x^(1/2)+3 fails the definition because the exponent of x is 1/2, a fractional number rather than a whole-number power.
The term x^(1/2) is the square root of x, and its exponent is explicitly 1/2. Therefore x^(1/2)+3 is not a polynomial in x, making option B correct. The issue is not the presence of the constant 3 or the plus sign; both are common in polynomials. For comparison, x^2+3 would be a polynomial because the powers 2 and 0 are non-negative integers.
Correct answer: A. क्योंकि x की घात ऋणात्मक है
Explanation: In a polynomial, the exponent of a variable must be 0 or a positive integer. In the given expression, the exponent of x is -3, so it is not a polynomial. Having a constant term such as 2 or having two terms does not prevent an expression from being a polynomial. Exam tip: An expression is not a polynomial if a variable has a negative, fractional, or irrational exponent.
Correct answer: D. 4
Explanation: The degree of a polynomial is the greatest exponent of the variable among terms with non-zero coefficients. Here, the exponents of x are 4, 2, and 0, and the greatest is 4. Therefore, the correct answer is 4. The values 1, 2, and 3 are not the highest exponent in this polynomial. Exam tip: A non-zero constant term has degree 0.
Correct answer: B. (\frac{3}{x}+5)
Explanation: In (\frac{3}{x}), (x) is in the denominator, so it is like (x^{-1}). Negative powers are not accepted in polynomials.
Correct answer: C. 3
Explanation: In a polynomial, terms are separated by the plus (+) or minus (−) signs. Here the terms are \(2x^5\), \(x\), and \(-6\). Therefore, there are 3 terms. The exponent of \(x\) being 1 does not affect the number of terms; neither the sum nor the highest exponent gives the term count. Exam tip: Count each expression separated by a + or − sign as one term.
Correct answer: A. x²
Explanation: The governing concept is identifying the power of each term in a polynomial. The variable here is x. In the term x², the exponent of x is 2, so its power is 2. In 2x, the variable is actually x¹, because an exponent of 1 is usually not written; its numerical coefficient 2 does not change the power. The terms 1 and the separate number 2 are constants and therefore have power 0. Comparing the powers gives 2, 1, and 0, with 2 being the greatest. Hence x², option A, is the correct term. A common mistake is to confuse the coefficient 2 in 2x with an exponent, but coefficient and power are different features.
Correct answer: A. \(3x+4\)
Explanation: A linear polynomial has degree 1. In \(3x+4\), the highest power of the variable \(x\) is 1, so it is a linear polynomial. \(x^2+1\) and \(x^3-2\) are quadratic and cubic polynomials respectively, while \(5\) is a constant polynomial. In an exam, identify the highest power of the variable to determine the degree.
Correct answer: A. \(4x^2-1\)
Explanation: In \(4x^2-1\), the highest power of \(x\) is 2. Hence, its degree is 2 and it is a quadratic polynomial. \(6x+1\) is linear because its degree is 1, while \(x^3-2\) is cubic. Exam tip: identify the type of a polynomial by checking the highest exponent of the variable.
Correct answer: A. \(x^3-4x+2\)
Explanation: A cubic polynomial is a polynomial of degree 3. In \(x^3-4x+2\), the highest power of the variable \(x\) is 3, so it is a cubic polynomial. Option B has degree 2, option C has degree 1, and option D is a constant polynomial. Exam tip: Identify the degree of a polynomial by looking for the highest power of its variable.
Correct answer: A. Polynomial
Explanation: \(2x^2+\sqrt{3}x+5\) is a polynomial in \(x\) because the exponents of \(x\) are \(2\), \(1\), and \(0\), all of which are non-negative integers. \(\sqrt{3}\) is a real number, so it can be a valid coefficient of \(x\). It is not a zero polynomial because its coefficients are not all zero. Exam tip: In a polynomial, variable exponents can only be \(0,1,2,\ldots\), while coefficients may be rational or irrational.
Correct answer: C. Not a polynomial
Explanation: The governing definition says that a polynomial in x can contain only non-negative integer powers of x, such as 0, 1, 2, and 3. Rewrite the radical as √x = x^(1/2). Although the term 2x has the valid integer power 1, the term x^(1/2) has a fractional power. A single fractional exponent is enough to make the complete expression non-polynomial. Therefore option C is correct. It is not linear because the radical term cannot be treated as an ordinary first-degree term, and it is not quadratic because no x² term is present. It is not constant because x appears in both terms. The coefficient 2 is allowed; the fractional exponent is the decisive issue.
Correct answer: C. 0
Explanation: The polynomial \(9x^2\) has only a term containing \(x\). A constant term has no variable in it. Since no such term is present, its value is taken as \(0\). Here, \(9\) is the coefficient of \(x^2\), not the constant term. Exam tip: Identify the term without a variable to find the constant term.
Correct answer: D. 0
Explanation: The terms of (x^4+x^2+x) are x^4, x^2, and x. There is no x^3 term, so the coefficient of x^3 is 0. Although 1 is the coefficient of x and x^2, it is not the coefficient of x^3. Exam tip: The coefficient of any missing power in a polynomial is always 0.
Correct answer: A. Yes, it is a polynomial
Explanation: Yes, it is a polynomial. Since x^0 = 1, the expression becomes 1 + 2x. The powers of x are 0 and 1, both of which are non-negative integers, so the expression is a polynomial. Option B is incorrect because a variable may have power 0 in a polynomial. Exam tip: In a polynomial, the powers of variables must be non-negative integers such as 0, 1, 2, and so on.