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All questions of Polynomials for Class 8 Exam

The degree of the polynomial x4 – 3x3 + 2x2 – 5x + 3 is:
  • a)
    2
  • b)
    1
  • c)
    4
  • d)
    3
Correct answer is option 'C'. Can you explain this answer?

Tarun Sengupta answered
**Explanation:**

The degree of a polynomial is the highest power of the variable in that polynomial. In this case, the polynomial is:

x^4 + 3x^3 + 2x^2 + 5x - 3

To find the degree of this polynomial, we need to identify the term with the highest power of x. Let's break down each term in the polynomial:

- The term x^4 has a power of 4.
- The term 3x^3 has a power of 3.
- The term 2x^2 has a power of 2.
- The term 5x has a power of 1.
- The constant term -3 has a power of 0.

As we can see, the term with the highest power of x is x^4. Therefore, the degree of the polynomial is 4.

Therefore, option C is the correct answer.

If (x-2) is the factor of x2 + 2x+ a, find the value of ‘a’.
  • a)
    a = -16
  • b)
    a = -8
  • c)
    a = 16
  • d)
    a = 8
Correct answer is option 'B'. Can you explain this answer?

Himaja Ammu answered
If x-2 is a factor then 2 is the zero of the polynomial
by substituting 2 in the given polynomial,we get
2^2+2(2)+a=0
8+a=0
a=-8

Which of the following are the factors of a2 + ab +bc + ca
  • a)
    (a + b) (a + c)
  • b)
    (a + b + c)
  • c)
    (a + b) (b + c)
  • d)
    (b + c) (c + a)
Correct answer is option 'A'. Can you explain this answer?

Nilotpal Unni answered
Factors of a2 ab bc ca

To find the factors of a2 ab bc ca, we need to factor out the common terms from all the terms. In this case, the common term is 'a'. So, we can write:

a2 ab bc ca = a(a b c + b c a)

Now, we need to factor the expression inside the parentheses. We can see that it contains two terms, 'abc' and 'bca', which have a common factor of 'bc'. So, we can write:

a(a b c + b c a) = a(bc(a + c))

Finally, we can factor out the common factor of 'a' and 'bc', which gives us:

a(bc(a + c)) = ab(a + c) ac(a + c)

Therefore, the factors of a2 ab bc ca are (a b) (a c).

 is equal to :-
  • a)
    1
  • b)
    (0.83)3 + (0.17)3
  • c)
    0
  • d)
    None of these
Correct answer is option 'A'. Can you explain this answer?

Shalini Shahi answered
Yes answer is 1. a=0.83 ,b=0.17 0.83×0.83×0.83 +0.17×0.17×0.17. / 0.83× 0.83+0.83× 0.17+0.17×0.17. = formula = a³+b³=( a+b)(a²-ab +b²) / a²-ab+ b² = cut the up and down a²-ab +b² = only a+b here ,add a+b =0.83+0.17= 1.00= 1, correct answer a) 1..

What is the product of (x+a) and (x+b)
a) x2 + (a+b)x + ab
b) x2 + (a+b)x - ab
c) x2 + (a+b)x - ab
d) x2+ (a-b)x + ab 
Correct answer is option 'A'. Can you explain this answer? 

Shail Kapoor answered
Product of (x + a) and (x + b)

The given expression is of the form (x + a)(x + b). To find the product, we can use the distributive property of multiplication over addition.

Using the distributive property, we can multiply the terms inside the parentheses:

(x + a)(x + b) = x(x + b) + a(x + b)

Now, we can simplify each term separately:

x(x + b) = x * x + x * b = x^2 + bx
a(x + b) = a * x + a * b = ax + ab

Putting it all together, we get:

(x + a)(x + b) = x^2 + bx + ax + ab

Simplifying further, we can combine like terms:

x^2 + bx + ax + ab = x^2 + (a + b)x + ab

Therefore, the product of (x + a) and (x + b) is x^2 + (a + b)x + ab, which is option 'A'.

The value of the polynomial 5x−4x2+3, when x = −1 is
  • a)
    - 6
  • b)
    1
  • c)
    9
  • d)
    -1
Correct answer is option 'A'. Can you explain this answer?

Zachary Foster answered
It is given that
p(x) = 5x - 4x² + 3
We have to find the value when x = -1
p(-1) = 5(-1) - 4(-1)² + 3
By further calculation
p(-1) = -5 - 4 + 3
So we get
p(-1) = -9 + 3
p(-1) = -6
Therefore, the value is -6.

A linear polynomial will have how many zeroes.
  • a)
    2
  • b)
    1
  • c)
    0
  • d)
    3
Correct answer is option 'B'. Can you explain this answer?

Rahul Kumar answered
A linear polynomial has 1 zero.
A quadratic polynomial has 2 zeroes.
A cubic polynomial has 3 zeroes.
In general, any polynomial has as many zeroes as its degree.

What are the two factors of quadratic polynomial x2-16x+64?
  • a)
    (x-16) and (x-64)
  • b)
    (x+8) and (x-8)
  • c)
    (x+16) and (x-4)
  • d)
    (x-8) and (x-8)
Correct answer is option 'D'. Can you explain this answer?

Solution:

To find the factors of the quadratic polynomial x2-16x+64, we can use the factorization formula for perfect square trinomials.

Formula: (a-b)2 = a2-2ab+b2

Comparing x2-16x+64 with the formula, we can see that a = x and b = 8.

Therefore, (x-8)2 = x2-16x+64

Taking the square root of both sides, we get:

x-8 = ±√(x2-16x+64)

x-8 = ±(x-8)

Now, we can solve for x in each case:

Case 1: x-8 = x-8

Simplifying, we get 0 = 0, which is always true. Therefore, this case gives us only one factor.

Factor 1: x-8

Case 2: x-8 = -(x-8)

Simplifying, we get 2x = 16, which gives us x = 8. Therefore, this case gives us another factor.

Factor 2: x-8

Thus, the two factors of the quadratic polynomial x2-16x+64 are (x-8) and (x-8), which can be written as (x-8)2.

Therefore, the correct answer is option D, (x-8) and (x-8).

If p(x) = x + 3, then p(x) + p(-x) is equal to
  • a)
    0
  • b)
    3
  • c)
    6
  • d)
    2x
Correct answer is option 'C'. Can you explain this answer?

Sanjana answered
we have , p(x) = x+3.........(1) Replacing x by -x ,we get p(-x)= -x+3 ............(2) adding the corresponding sides of (1)and (2),we get p(x)+p(-x) = 6

The expansion of (2a – 3b + 5c)2.
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'C'. Can you explain this answer?

Gaurav Kumar answered
The expansion of (2a - 3b + 5c)² -: (2a)² + (- 3b)² + (5c)² + 2× 2a × (-3b) + 2× (-3b)× 5c + 2× 5c + 2a. = 4a² + 9b² + 25c² - 12ab - 30bc + 20ac

For two polynomials p(x) and q(x), x-a and x-b are their factors, respectively.Which of the following is true?​
  • a)
    p(a)+q(b) = 0
  • b)
    p(a) x q(b) = 2
  • c)
    p(a) x q(b) = 1
  • d)
    p(a) + q(b) = 1
Correct answer is option 'A'. Can you explain this answer?

Ritika Kumar answered
Solution:

Given that x-a and x-b are factors of polynomials p(x) and q(x) respectively.

This implies that,

p(a) = 0 and q(b) = 0

We need to find the expression that is true from the given options.

Option A: p(a)q(b) = 0

Since p(a) and q(b) both are zero, the product of p(a) and q(b) is also zero. Hence, option A is correct.

Option B: p(a) x q(b) = 2

This is not true for any polynomial p(x) and q(x).

Option C: p(a) x q(b) = 1

This is not true for any polynomial p(x) and q(x).

Option D: p(a) q(b) = 1

This is not true for any polynomial p(x) and q(x).

Therefore, the correct option is A.

If (x-1) is a factor of ax – a, then find the value of a​
  • a)
    a = 1
  • b)
    a = 2
  • c)
    a = 3
  • d)
    All values of a
Correct answer is option 'D'. Can you explain this answer?

Gaurav Kumar answered
ANSWER :- d
Solution :- f(x) = ax - a……………………..(1)
x - 1 = 0
x = 1
Putting in eq(1)
(1)x - 1 => x - 1
 
For eg :- if we put x = 100
Putting in eq(1)
(100)x - 100 => x - 100
So, all the values of a

When the polynomial x3 + 3x2 + 3x + 1 is divided by x + 1, the remainder is :-
  • a)
    1
  • b)
    8
  • c)
    0
  • d)
    - 6
Correct answer is option 'C'. Can you explain this answer?

Hansa Sharma answered
The zero of x + 1 is –1
                And by remainder theorem, when
                p(x) = x3 + 3x2 + 3x + 1 is divided by x + 1, then remainder is p(–1).
                ∴ p(–1) = (–1)3 + 3 (–1)2 + 3(–1) + 1
                = –1 + (3 × 1) + (–3) + 1
                = –1 + 3 – 3 + 1
                = 0
                Thus, the required = 0

The value of 101 x 99 is
  • a)
    8998
  • b)
    1111
  • c)
    9889
  • d)
    9999
Correct answer is option 'D'. Can you explain this answer?

Arun Sharma answered
(100+1)×(100 - 1) it is the formula of a²-b² so, (100)² -(1)² = 10000-1 = 9999.

What is the value 83 – 33 (without solving the cubes)?​
  • a)
    485
  • b)
    845
  • c)
    458
  • d)
    854
Correct answer is option 'A'. Can you explain this answer?

Pranab Datta answered
The value 83 is a positive integer that represents a quantity or amount. It is a prime number and comes after 82 and before 84 in the number sequence.

If P(x) = 10x−4x2−3, then the value of p(0)+p(1) is
  • a)
    1
  • b)
    3
  • c)
    -3
  • d)
    0
Correct answer is option 'D'. Can you explain this answer?

I'm sorry, your question is incomplete. Please provide more details or context for me to understand and respond accurately.

  • a)
    2p = r
  • b)
    p = 2r
  • c)
    p = r
  • d)
    none of these
Correct answer is option 'C'. Can you explain this answer?

Amit Sharma answered
Let f(x) = px2 + 5 x + r
If (x - 2) is a factor of f (x), then by factor theorem
f(2) = 0 | x - 2 = 0 ⇒ x = 2
⇒ p(2)2 + 5(2) + r = 0
⇒ 4p + r + 10 = 0    ...(1)
If  is a factor of f (x), then by factor theorem,
Subtracting (2) from (1), we get
3p - 3r = 0
⇒    p = r

The zero of the polynomial (x−2)2−(x+2)2 is
  • a)
    1
  • b)
    -2
  • c)
    2
  • d)
    0
Correct answer is option 'D'. Can you explain this answer?

Sanjana answered
{(x)² + (2)² - 2× x ×2} - {(x)² + (2)² + 2 × x×2} = (x² + 4 - 4x) - (x² + 4 + 4x) = x² + 4 - 4x - x²- 4 - 4x = 0.........ans

√2 is a polynomial of degree
  • a)
    1
  • b)
    0
  • c)
    2
  • d)
    √2
Correct answer is option 'B'. Can you explain this answer?

Vivek Rana answered
The highest power of the variable is known as the degree of the polynomial.

√2x^0 = √2
hence the degree of the polynomial is zero.

Find the zero of the polynomial of p (x) = ax + b ; a ≠ 0
  • a)
    b/a
  • b)
    a/b
  • c)
    -b/a
  • d)
    -a/b
Correct answer is 'C'. Can you explain this answer?

Saranya Nair answered
Finding the Zero of a Polynomial

To find the zero of a polynomial, we need to solve for x when p(x) = 0. In other words, we need to find the value of x that makes the polynomial equal to zero.

Given p(x) = ax^b, where a ≠ 0 and b ≥ 1, we need to find the zero of the polynomial.

Solution

To find the zero of the polynomial, we need to solve for x when p(x) = 0. Substituting the given polynomial, we get:

ax^b = 0

Since a ≠ 0 and b ≥ 1, we know that the only value of x that satisfies the equation is x = 0. Therefore, the zero of the polynomial is x = 0.

Option (c) is the correct answer, as it corresponds to x = 0.

Explanation

The given polynomial p(x) = ax^b has only one term, which is ax^b. This term can only equal zero if x = 0, since any non-zero value of x raised to a positive power will be non-zero.

Therefore, the zero of the polynomial is x = 0, which corresponds to option (c).

If the polynomial 2x3 – 3x2 + 2x – 4 is divided by x – 2, then the remainder is :-
  • a)
    - 4
  • b)
    4
  • c)
    -40
  • d)
    2
Correct answer is option 'B'. Can you explain this answer?

Mahi Sharma answered
3x2 - 5x + 7 is divided by x - 2, the remainder is:

To find the remainder, we can use the remainder theorem which states that if a polynomial f(x) is divided by x - a, the remainder is equal to f(a).

Therefore, if we substitute x = 2 in the given polynomial, we get:

2(2)3 - 3(2)2 - 5(2) + 7 = 16 - 12 - 10 + 7 = 1

Hence, the remainder when the polynomial 2x3 + 3x2 - 5x + 7 is divided by x - 2 is 1.

(a – b)3 + (b – c)3 + (c – a)3 is equal to :-
  • a)
    3abc
  • b)
    3a3b3c3
  • c)
    3(a – b) (b – c) (c – a)
  • d)
    [a – (b + c)]3
Correct answer is option 'C'. Can you explain this answer?

Indu Gupta answered
Let x = (a – b), y = (b – c) and z = (c – a)
Consider, x + y + z = (a – b) + (b – c) + (c – a) = 0
⇒ x3 + y3 + z3 = 3xyz
That is (a – b)3 + (b – c)3 + (c – a)3 = 3(a – b)(b – c)(c – a)

Factorize the quadratic polynomial by splitting the middle term: y2 – 4 y –21​
  • a)
    (y – 7) (y – 3)
  • b)
    (y – 7) (y + 3)
  • c)
    (y + 7) (y – 3)
  • d)
    (y + 7) (y + 3)
Correct answer is option 'B'. Can you explain this answer?

Ujwal Das answered
+ 7y + 10

To factorize this quadratic polynomial, we need to find two numbers that multiply to give the constant term (10) and add to give the coefficient of the middle term (7).

The factors of 10 are:

1 x 10
2 x 5

Since we need the sum of the factors to be 7, we can see that 2 and 5 are the two numbers we are looking for.

So, we can rewrite the middle term as 2y + 5y:

y2 + 2y + 5y + 10

Now, we can group the first two terms and the last two terms together and factorize each group separately:

y(y + 2) + 5(y + 2)

Notice that both groups have a common factor of (y + 2), so we can factorize it out:

(y + 2)(y + 5)

Therefore, the factored form of the quadratic polynomial y2 + 7y + 10 is (y + 2)(y + 5).

Can you explain the answer of this question below:

What should be subtracted to x2+2x+2 to make it a perfect square?

  • A:

    1

  • B:

    3

  • C:

    2

  • D:

    4

The answer is a.

Janhavi Sen answered
Solution:
To make x^2 + 2x + 2 a perfect square, we need to find a number 'a' that satisfies the following equation:
(x + a)^2 = x^2 + 2x + 2
Expanding the left-hand side of the equation, we get:
x^2 + 2ax + a^2 = x^2 + 2x + 2
Comparing the coefficients of x^2, x, and the constant term on both sides, we get:
a^2 = 2 (coefficient of x^2 on both sides is 1)
2a = 2 (coefficient of x on both sides is 2)
a = 1 (constant terms on both sides are equal)
Therefore, we need to subtract 1 from x^2 + 2x + 2 to make it a perfect square.
Hence, the answer is option 'A'.

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