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The name "polynomial" comes from the words "poly" (meaning many) and "nomial" (meaning phrase), so it means "many terms."
- A polynomial is made up of solely added, subtracted, and multiplied terms.
- ax² + bx + c is the form of a quadratic polynomial in x with real coefficients, where a, b, and c are real numbers with a = 0.
- The degree of a polynomial refers to the variable's highest exponent in the polynomial. 2x² + 4 is an example where the degree is 2.
- Linear, quadratic, and cubic polynomials have the degrees 1, 2, and 3 polynomials, respectively.
- A polynomial can have terms with constants such as 5, -2, and others, as well as variables like x and y and exponents such as 2 in y².
- Addition, subtraction, and multiplication can be used to combine these, but not division.
- The x-coordinates of the locations where the graph of y = p(x) contacts the x-axis are the zeroes of polynomial p(x).
- If α and β are the zeroes of the quadratic polynomial ax² + bx + c, then:
- If α, β, γ are the zeroes of the cubic polynomial ax³ + bx² + cx + d = 0, then:
- Zeroes, also known as α, β, γ, follow the rules of algebraic identities, i.e.,
(α + β)² = α² + β² + 2αβ
∴(α² + β²) = (α + β)² – 2αβ
- If p(x) and g(x) are any two polynomials with g(x) = 0, then p(x) = g(x) * q + r is the division algorithm:
Dividend = Divisor x Quotient + Remainder
The video below explains this:
Polynomials Detailed Video Explanation:
Question 1: If the zeroes of the quadratic polynomial ay² + by + c, c ≠ 0 are equal, then
- c and b have opposite signs
- c and a have opposite signs
- c and b have the same signs
- c and a have the same signs
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Answer: (d) c and a have the same signs
Explanation: Discriminant will be equal to zero for equal roots:
b² - 4ac = 0
b² = 4ac
ac = b²/4
ac > 0 (square of any number cannot be negative)
Question 2: If the sum of zeroes of the quadratic polynomial 3x² – kx + 6 is 3, then the value of k is:
- 4
- 5
- 7
- 9
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Answer: (d) 9
Explanation: Here a = 3, b = -k, c = 6
Sum of the zeroes, (α + β) = -b/a = 3 …..(given)
⇒ −(−k)/3 = 3
⇒ k = 9
Question 3: The degree of the polynomial, x5 – 2x2 + 2 is:
- 2
- 4
- 1
- 5
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Answer: (d) 5
Explanation: In every polynomial, the highest power of the variable is called a degree.
Question 4: If p(x) is a polynomial of degree one and p(y) = 0, then y is said to be:
- Zero of p(x)
- Value of p(x)
- Constant of p(x)
- None of the above
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Answer: (a) Zero of p(x)
Explanation: Let p(x) = mx + n
Put x = y
p(y) = my + n = 0
So, y is zero of p(x).
Question 5: A polynomial's zeros can be represented graphically. The number of polynomial zeros equals the number of points on the graph of the polynomial:
- Intersects y-axis
- Intersects x-axis
- Intersects y-axis or x-axis
- None of the above
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Answer: (b) Intersects x-axis
Explanation: The number of zeroes of a polynomial is equal to the number of points where the graph of polynomial intersects the x-axis.
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Question 6: A polynomial of degree p has:
- Only one zero
- At least p zeroes
- More than p zeroes
- At most p zeroes
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Answer: (d)
Explanation: A polynomial's maximum number of zeroes equals the polynomial's degree.
Question 7: If α and β are the zeroes of a polynomial such that α + β = -6 and αβ = 5, then the polynomial is:
- x² + 6x + 5 = 0
- x² + 6x - 5 = 0
- x² - 6x + 5 = 0
- x² - 6x - 5 = 0
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Answer: (a) x² + 6x + 5 = 0
Explanation: Quadratic polynomial is x² – Sx + P = 0, where S is the sum and P is the product
⇒ x² – (-6)x + 5 = 0
⇒ x² + 6x + 5 = 0
Question 8: Zeros of p(x) = x² - 27 are:
- ± 3√3
- ± 9√3
- ± 7√3
- None of the above
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Answer: (a)
Explanation: x² - 27 = 0
x² = 27
x = √27
x = ±3√3
Question 9: The quadratic polynomial whose zeroes are 3 + √2 and 3 – √2 is:
- x² – 6x - 7
- x² + 6x + 7
- x² – 6x + 7
- x² + 6x - 7
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Answer: (c) x² – 6x + 7
Explanation: S is the sum of zeroes and P is the product of zeroes:
S = (3 + √2) + (3 – √2) = 6
P = (3 + √2) x (3 – √2) = (3)² – (√2)² = 9 – 2 = 7
So, Quadratic polynomial = x² – Sx + P = x² – 6x + 7
Question 10: If a quadratic polynomial's discriminant, D, is greater than zero, the polynomial has:
- two real and equal roots
- two real and unequal roots
- imaginary roots
- no roots
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Answer: (b) two real and unequal roots
Explanation: If the discriminant of a quadratic polynomial, D > 0, then the polynomial has two real and unequal roots.
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