Question

EXERCISE 4.1
1. Which of the following expressions are polynomials in one variable and which are
not? State reasons for your answer.
(i) 4x2 – 3x + 7
2
(ii) y2 + 2
(ii) 317 +
(iv) y +
(v) x10+ y3 + 50​

Answer 1

The equation 4x²–3x+7 can be written as 4x²–3x1+7x0

Since x is the only variable in the given equation and the powers of x (i.e., 2, 1 and 0) are whole numbers, we can say that the expression 4x²–3x+7 is a polynomial in one variable.

Answer 2

Question :-

Which of the following expressions are polynomials in one variable and which are not? State reasons for your answer.

(i) 4x^2 – 3x + 7

(ii) y^2 + √2

(iii) 3 √t + t√2

(iv) y+ 2/y

(v) x^10+ y^3+t^50

Answer :-

(i) We have 4x^2 – 3x + 7 = 4x^2 – 3x + 7x^0

It is a polynomial in one variable i.e., x

because each exponent of x is a whole number.

(ii) We have y^2 + √2 = y^2 + √2y^0

It is a polynomial in one variable i.e., y

because each exponent of y is a whole number.

(iii) We have 3 √t + t√2 = 3 √t^1/2 + √2.t

It is not a polynomial, because one of the exponents of t is 1/2,

which is not a whole number.

(iv) We have y + y+2/y = y + 2.y^-1

It is not a polynomial, because one of the exponents of y is -1,

which is not a whole number.

(v) We have x^10+  y^3 + t^50

Here, exponent of every variable is a whole number, but x^10 + y^3 + t^50 is a polynomial in x, y and t, i.e., in three variables.

So, it is not a polynomial in one variable.

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