Polynomials
Zeros of quadratic and cubic polynomials, relations between zeros and coefficients, division algorithm — Maharashtra SSC Algebra
Board Exam Tips
- →Sum and product of zeros are compulsory in every Algebra paper — form-a-polynomial is a 2-mark starter.
- →For cubic, sum of zeros = -b/a, sum of products taken two at a time = c/a, product of zeros = -d/a. Memorise all three.
- →Marathi terms: बहुपदी (polynomial), शून्ये (zeros), भागाकार अल्गोरिदम (division algorithm).
- →Draw parabola shape: opens up if a > 0, opens down if a < 0. Number of zeros = number of x-axis crossings.
- →Verify computed zeros by substituting back into p(x) — catches sign mistakes and gives 1 confirmation mark.
📐 Formulas(10)
Standard Form of Quadratic Polynomial★ Board fav
| Symbol | Meaning |
|---|---|
| Real coefficients with a ≠ 0 |
Sum of Zeros (Quadratic)★ Board fav
| Symbol | Meaning |
|---|---|
| Zeros (roots) of the quadratic |
Product of Zeros (Quadratic)★ Board fav
Quadratic Polynomial from Given Zeros
Sum of Zeros (Cubic)
Sum of Products Taken Two at a Time (Cubic)
Product of Zeros (Cubic)
Division Algorithm for Polynomials
Remainder Theorem
Factor Theorem
✏️ Solved Examples
If the zeros of the polynomial p(x) = x² − 3x − 10 are α and β, verify the relations between zeros and coefficients.
Factorise
Find a quadratic polynomial whose zeros are 3 + √2 and 3 − √2.
Sum of zeros
If two zeros of the polynomial p(x) = x³ − 4x² − 7x + 10 are −2 and 1, find the third zero.
Compare with ax³ + bx² + cx + d
⚠️ Traps & Common Mistakes
- 1
Writing α + β = b/a (missing negative sign)
✓Sum of zeros = -b/a. The minus is essential.
- 2
Applying sum/product formulas without dividing by a
✓Use α + β = -b/a and αβ = c/a. When a = 1 the division is trivial — still write it.
- 3
Using the same product sign for cubics as for quadratics
✓For cubics, αβγ = -d/a (negative). For quadratics, αβ = c/a (positive).
- 4
Ignoring the leading coefficient k when forming a polynomial from zeros
✓p(x) = k(x² − (α+β)x + αβ). Any k ≠ 0 works — take k = 1 for the simplest form.
- 5
Confusing degree with number of terms
✓Degree = highest power of x; e.g. x² + x + 1 has degree 2, three terms.
- 6
Concluding a polynomial has 3 zeros just because it is cubic
✓Real zeros can be fewer (1 or 2). The 'fundamental' count of 3 includes complex roots.
🎯 Practice Yourself
- Q1
Find the zeros of p(x) = x² − 2x − 8 and verify sum/product of zeros.
- Q2
Form the polynomial whose zeros are -3 and 4.
- Q3
Divide p(x) = x³ − 3x² + 5x − 3 by g(x) = x − 1 and find quotient and remainder.
- Q4
If α, β are zeros of x² + 5x + 6, find (i) 1/α + 1/β, (ii) α² + β².
- Q5
Find k so that x = 2 is a zero of p(x) = x³ − kx² + 3x − 4.
- Q6
If α and β are zeros of x² − 6x + 8, form the polynomial whose zeros are 2α and 2β.
📝 Notes
Polynomials
Polynomials sit at the crossroads of algebra and coordinate geometry. Their zeros tell us where the curve meets the x-axis, and the coefficients encode the sum, product and combinations of those zeros — long before we actually solve the equation.
SSC angle
Maharashtra Board Algebra places one direct 2-mark and one 3-mark polynomial question every year:
- 2-mark: verify relations between zeros and coefficients.
- 3-mark: form a polynomial from given zeros, or find missing zero of a cubic.
- HOTS: apply division algorithm to find quotient and remainder, or use factor theorem.
Choose the right form
- When zeros are known → p(x) = x² − (sum)x + (product).
- When one factor is known → use division algorithm.
- When one zero is given → factor out (x − a), then solve the resulting quadratic.
Handy identities that save time
- α² + β² = (α + β)² − 2αβ
- (α − β)² = (α + β)² − 4αβ
- α³ + β³ = (α + β)³ − 3αβ(α + β)
- 1/α + 1/β = (α + β)/(αβ)
Number of real zeros vs degree
- Linear (degree 1): 1 real zero.
- Quadratic (degree 2): 0, 1 (repeated) or 2 real zeros — count using discriminant.
- Cubic (degree 3): at least 1 real zero; up to 3.
Board vs CBSE
Both boards teach the same content. Maharashtra SSC leans on Vieta-style questions (sum/product manipulations) and uses the term "बहुपदी" freely in Marathi-medium paper.
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