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Mathematics

Identify which of the following expressions are polynomials. If so, write their degrees.

(i) 23x47x+15\dfrac{2}{3}x^4 - 7x + 15

(ii) 8x2 - 3x + 6√x + 1

(iii) 5x2 - 2x\dfrac{2}{x} + 7

(iv) 9x2y2 - 3xy2 + 5x2y - 6x

(v) 6p4 - p3q2 + pq3 + q4

(vi) 4x5 - 7x5y + 3xy4 + 8y5

(vii) ab2 - 7a2\dfrac{7}{a^2} + 5b2 + 6

Algebraic Expressions

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Answer

(i) 23x47x+15\dfrac{2}{3}x^4 - 7x + 15

All powers of x are whole numbers.

The highest power of x is 4.

Yes, it is a polynomial. Degree = 4

(ii) 8x2 - 3x + 6√x + 1

The term 6√x can be written as 6x1/2, 1/2 is not a whole number.

∴ It is not a polynomial.

(iii) 5x2 - 2x\dfrac{2}{x} + 7

The term 2x\dfrac{2}{x} can be written as 2x-1, power of x is a negative integer.

∴ It is not a polynomial.

(iv) 9x2y2 - 3xy2 + 5x2y - 6x

All powers of x and y are whole numbers.

Degrees of terms:

9x2y2 → 2 + 2 = 4

3xy2 → 1 + 2 = 3

5x2y → 2 + 1 = 3

6x → 1

The highest degree is 4.

Yes, it is a polynomial. Degree = 4

(v) 6p4 - p3q2 + pq3 + q4

All powers of p and q are whole numbers.

Degrees of terms:

6p4 → 4

p3q2 → 3 + 2 = 5

pq3 → 1 + 3 = 4

q4 → 4

The highest degree is 5.

Yes, it is a polynomial. Degree = 5

(vi) 4x5 - 7x5y + 3xy4 + 8y5

All powers of x and y are whole numbers.

Degrees of terms:

4x5 → 5

7x5y → 5 + 1 = 6

3xy4 → 1 + 4 = 5

8y5 → 5

The highest degree is 6.

Yes, it is a polynomial. Degree = 6

(vii) ab2 - 7a2\dfrac{7}{a^2} + 5b2 + 6

The term 7a2\dfrac{7}{a^2} means 7a-2, power of a is a negative integer.

∴ It is not a polynomial.

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