Class 9 Maths
Polynomials
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:
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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?
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