find the relationship between zeroes and coefficients of the polynomial x2 – 2x-8
To find the relationship between the zeroes and the coefficients of the polynomial x2−2x−8x^2 – 2x – 8, follow these steps:
Step 1: Identify the given quadratic polynomial
The given polynomial is:
x2−2x−8x^2 – 2x – 8
Here, the general form of a quadratic polynomial is:
ax2+bx+cax^2 + bx + c
Comparing, we get:
- a=1a = 1
- b=−2b = -2
- c=−8c = -8
Step 2: Find the zeroes of the polynomial
To find the zeroes, solve:
x2−2x−8=0x^2 – 2x – 8 = 0
Factorizing,
(x−4)(x+2)=0(x – 4)(x + 2) = 0
Setting each factor equal to zero,
x−4=0 or x+2=0
So, the zeroes of the polynomial are 4 and -2.
Step 3: Verify the Relationship Between Zeroes and Coefficients
According to Vieta’s formulas:
- Sum of the zeroes:
α+β=−baSubstituting values,
4+(−2)=−−21=2Matches the formula.
- Product of the zeroes:
α⋅β=caSubstituting values,
4×(−2)=−81=−84 \times (-2) = \frac{-8}{1} = -8Matches the formula.
Conclusion
For the quadratic polynomial x2−2x−8x^2 – 2x – 8, the relationship between the zeroes and the coefficients is:
- Sum of zeroes (α+β)=−ba=2(\alpha + \beta) = -\frac{b}{a} = 2
- Product of zeroes (α⋅β)=ca=−8(\alpha \cdot \beta) = \frac{c}{a} = -8