NCERT Solutions
Class 9 Maths
Polynomials
Electric charges

Ex.2.1 Q.1

Which of the following expressions are polynomials in one variable and which are not?

State reasons for your answer.

(1) 4x2 - 3x + 7     

(2) y2 + √2       

(3) 3√t + t√2          

(4) y +              

(5) x10 + y3 + t50

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Ex.2.1 Q.2

Write the coefficients of x2 in each of the following:

(1) 2 + x2 + x              

(2) 2 - x2 + x3             

(3)  × x2 + x              

(4) √2x - 1

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Ex.2.1 Q.3

Give one example each of a binomial of degree 35, and of a monomial of degree 100.

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Ex.2.1 Q.4

Write the degree of each of the following polynomials:

(1) 5x3 + 4x2 + 7x                

(2) 4 - y2               

(3) 5t - √7              

(4) 3

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Ex.2.1 Q.5

Classify the following as linear, quadratic and cubic polynomials:

(1) x2 + x    

(2) x - x3       

(3) y + y2 + 4           

(4) 1 + x      

(5) 3t        

(6) r2          

(7) 7x3

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Ex.2.2 Q.1

Find the value of the polynomial 5x - 4x2 + 3 at

(1) x = 0                            

(2) x = -1                        

(3) x = 2

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Ex.2.2 Q.2

Find p (0), p (1) and p (2) for each of the following polynomials:

(1) p(y) = y2 – y + 1                      

(2) p(t) = 2 + t + 2t2 – t3

(3) p(x) = x3                                 

(4) p(x) = (x – 1) (x + 1)

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Ex.2.2 Q.3

Verify whether the following are zeroes of the polynomial, indicated against them.

(1) p(x) = 3x + 1, x = -                       

(2) p(x) = 5x – π, x =               

(3) p(x) = x2 – 1, x = 1, –1                                     

(4) p(x) = (x + 1) (x – 2), x = – 1, 2     

(5) p(x) = x2, x = 0                        

(6) p(x) = lx + m, x = -

(7) p(x) = 3x2 - 1, x = - ,     

(8) p(x) = 2x + 1, x =

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Ex.2.2 Q.4

Find the zero of the polynomials in each of the following cases:

(1) p(x) = x + 5           

(2) p(x) = x – 5               

(3) p(x) = 2x + 5        

(4) p(x) = 3x – 2

(5) p(x) = 3x              

(6) p(x) = ax, a ≠ 0        

(7) p(x) = cx + d, c ≠ 0, c, d are real numbers.

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Ex.2.3 Q.1

Find the remainder when x3 + 3x2 + 3x + 1 is divided by

(1) x + 1          

(2) x –              

(3) x               

(4) x + π                 

(5) 5 + 2x

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Ex.2.3 Q.2

Find the remainder when x3 – ax2 + 6x – a is divided by x – a.

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Ex.2.3 Q.3

Check whether 7 + 3x is a factor of 3x2 + 7x.

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Ex.2.4 Q.1

Determine which of the following polynomials has (x + 1) a factor:

(1) x3 + x2 + x + 1                                                   

(2) x4 + x3 + x2 + x + 1

(3) x4 + 3x3 + 3x2 + x + 1                                    

(4) x3 – x2 – (2 + √2) x + √2

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Ex.2.4 Q.2

Use the Factor Theorem to determine whether g(x) is a factor of p(x) in each of the following cases:

(1) p(x) = 2x3 + x2 – 2x – 1, g(x) = x + 1

(2) p(x) = x3 + 3x2 + 3x + 1, g(x) = x + 2

(3) p(x) = x3 - 4x2 + x + 6, g(x) = x - 3

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Ex.2.4 Q.2

Find the value of k, if x – 1 is a factor of p(x) in each of the following cases:

(1) p(x) = x2 + x + k   

(2) p(x) = 2x2 + kx + √2   

(3) p(x) = kx2 – √2x + 1    

(4) p(x) = kx2 – 3x + k

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Ex.2.4 Q.3

Find the value of k, if x – 1 is a factor of p(x) in each of the following cases:

(1) p(x) = x2 + x + k   

(2) p(x) = 2x2 + kx + √2   

(3) p(x) = kx2 – √2x + 1    

(4) p(x) = kx2 – 3x + k

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Ex.2.4 Q.4

Factorise:

(1) 12x2 – 7x + 1        

(2) 2x2 + 7x + 3           

(3) 6x2 + 5x – 6           

(4) 3x2 – x – 4

 

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Ex.2.4 Q.5

Factorise:

(1) x3 – 2x2 – x + 2    

(2) x3 – 3x2 – 9x – 5     

(3) x3 + 13x2 + 32x + 20           

(4) 2y3 + y2 – 2y – 1

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Ex.2.5 Q.1

Use suitable identities to find the following products:

(1) (x + 4) (x + 10)                         

(2) (x + 8) (x – 10)                           

(3) (3x + 4) (3x – 5)        

(4) (y2 + ) (y2  )              
(5) (3 – 2x) (3 + 2x)

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Ex.2.5 Q.2

Evaluate the following products without multiplying directly:

(1) 103 × 107                   

(2) 95 × 96                   

(3) 104 × 96

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Ex.2.5 Q.2

Factorise the following using appropriate identities:

(1) 9x2 + 6xy + y2                   

(2) 4y2 – 4y + 1                      

(3) x2

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Ex.2.5 Q.4

Expand each of the following, using suitable identities:

(1) (x + 2y + 4z)2                       

(2) (2x – y + z)2                    

(3) (–2x + 3y + 2z)2

(4) (3a – 7b – c)2                    

(5) (–2x + 5y – 3z)2               

(6) [  –  + 1]2

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Ex.2.5 Q.5

Factorise:

(1) 4x2 + 9y2 + 16z2 + 12xy – 24yz – 16xz

(2) 2x2 + y2 + 8z2 – 2√2 xy + 4√2 yz – 8xz

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Ex.2.5 Q.6

Write the following cubes in expanded form:

(1) (2x + 1)3               

(2) (2a – 3b)3                

(3) [  + 1]3               

(4) [x – ]3

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Ex.2.5 Q.7

Evaluate the following using suitable identities:

(1) (99)3                      

(2) (102)3                      

(3) (998)3

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Ex.2.5 Q.8

Factorise each of the following:

(1) 8a3 + b3 + 12a2b + 6ab2      

(2) 8a3 – b3 – 12a2b + 6ab2      

(3) 27 – 125a3 – 135a + 225a2

(4) 64a3 – 27b3 – 144a2 b + 108ab2            

(5) 27p3  –  +

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Ex.2.5 Q.9

Verify:

(1) x3 + y3 = (x + y) (x2 – xy + y2)

(2) x3 - y3 = (x - y) (x2 + xy + y2)

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Ex.2.5 Q.10

Factorise each of the following:

(1) 27y3 + 125z3                             

(2) 64m3 – 343n3

[Hint: See Question 9.]

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Ex.2.5 Q.11

Factorise: 27x3 + y3 + z3 – 9xyz.

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Ex.2.5 Q.12

Verify that x3 + y3 + z3 – 3xyz = ( ) × (x + y + z) × [(x - y)2 + (y - z)2 + (z - x)2]

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Ex.2.5 Q.13

If x + y + z = 0, show that x3 + y3 + z3 = 3xyz.

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Ex.2.5 Q.14

Without actually calculating the cubes, find the value of each of the following:

(1) (–12)3 + (7)3 + (5)3                        

(2) (28)3 + (–15)3 + (–13)3

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Ex.2.5 Q.15

Give possible expressions for the length and breadth of each of the following rectangles,

in which their areas are given:     

1.jpg

 

 

 

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Ex.2.5 Q.16

What are the possible expressions for the dimensions of the cuboids whose volumes are given below?

2.jpg                                   

 

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Complete NCERT Solutions: Classes 6 to 12, All Chapters

NCERT Solution for class 6
NCERT Solution for class 7
NCERT Solution for class 8
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NCERT Solution for class 10
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