Question 1. Which of the following expressions are polynomials in one variable and which are not? State reasons for your answer.
(i) 4x2 – 3x + 7
(ii) y2 + √2
(iii) 3√t + t√2
(iv) y + 2/y
(v) x10 + y3 + t50
Solution:
(i) The algebraic expression 4x2 – 3x + 7 can be written as 4x2 – 3x + 7x0
As we can see, all exponents of x are whole numbers,
So, the given expression 4x2 – 3x + 7 is polynomial in one variable.
(ii) The algebraic expression y2 + √2 can be written as y2 + √2y0
As we can see, all exponents of y are whole numbers,
So, the given expression y2 + √2 is polynomial in one variable.
(iii) The algebraic expression 3 √t + t√2 can be written as 3 t1/2 + √2.t
As we can see, one exponent of t is 1/2, which is not a whole number,
So, the given expression 3 √t + t√2 is not a polynomial in one variable.
(iv) The algebraic expression y + 2/y can be written as y + 2.y-1
As we can see, one exponent of y is -1, which is not a whole number,
So, the given expression y+ 2/y is not a polynomial in one variable.
(v) The given algebraic expression is x10+ y3+ t50
As we can see, the expression contains three variables i.e x, y, and t,
So, the given expression x10 + y3 + t50 is not a polynomial in one variable.
Question 2. Write the coefficients of x2 in each of the following
(i) 2 + x2 + x
(ii) 2 – x2 + x3
(iii) pi/2 x2 + x
(iv) √2x – 1
Solution:
(i) The given algebraic expression is 2 + x2 + x
As we can clearly see, the coefficient of x2 is 1.
(ii) The given algebraic expression is 2 – x2 + x3
As we can clearly see, the coefficient of x2 is -1.
(iii) The given algebraic expression is pi/2 x2 + x
As we can clearly see, the coefficient of x2 is pi/2.
(iv) The given algebraic expression is √2 x — 1
As we can clearly see, the coefficient of x2 is 0.
Question 3. Give one example each of a binomial of degree 35, and of a monomial of degree 100.
Solution:
A Binomial having degree 35 is 4x35 + 50
A Monomial having degree 100 is 3t100pi
Question 4. Write the degree of each of the following polynomials
(i) 5x3 + 4x2 + 7x
(ii) 4 – y2
(iii) 5t – √7
(iv) 3
Solution:
The highest power of a variable in the given expression is known as the Degree of the polynomial
(i) The given expression is 5x3 + 4x2 + 7x
As we can clearly see, the highest power of variable x is 3,
So, the degree of given polynomial 5x3+4x2 + 7x is 3.
(ii) The given expression is 4 – y2
As we can clearly see, the highest power of variable y is 2,
So, the degree of given polynomial 4 – y2 is 2.
(iii) The given expression is 5t – √7
As we can clearly see, the highest power of variable t is 1,
So, the degree of given polynomial 5t – √7 is 1.
(iv) The given expression 3 can be written as 3x0
As we can clearly see, the highest power of variable x is 0,
So, the degree of given polynomial 3 is 0.
Question 5. Classify the following as linear, quadratic, and cubic polynomials
(i) x2 + x
(ii) x – x3
(iii) y + y2 + 4
(iv) 1 + x
(v) 3t
(vi) r2
(vii) 7x3
Solution:
(i) Since the degree of given polynomial x2 + x is 2,
So, it is a Quadratic Polynomial.
(ii) Since the degree of given polynomial x – x3 is 3,
So, it is a Cubic Polynomial.
(iii) Since the degree of given polynomial y + y2 + 4 is 2,
So, it is a Quadratic Polynomial.
(iv) Since the degree of given polynomial 1 + x is 1,
So, it is a Linear Polynomial.
(v) Since the degree of given polynomial 3t is 1,
So, it is a Linear Polynomial.
(vi) Since the degree of given polynomial r2 is 2,
So, it is a Quadratic Polynomial.
(vii) Since the degree of given polynomial 7x3 is 3,
So, it is a Cubic Polynomial.