The polynomial $2x^3 + 6x^2 - 7x - 10$ has zeros $\alpha$, $\beta$ and $\gamma$ - HSC - SSCE Mathematics Extension 1 - Question 4 - 2018 - Paper 1
Question 4
The polynomial $2x^3 + 6x^2 - 7x - 10$ has zeros $\alpha$, $\beta$ and $\gamma$.
What is the value of $\alpha\beta\gamma(\alpha + \beta + \gamma)$?
Worked Solution & Example Answer:The polynomial $2x^3 + 6x^2 - 7x - 10$ has zeros $\alpha$, $\beta$ and $\gamma$ - HSC - SSCE Mathematics Extension 1 - Question 4 - 2018 - Paper 1
Step 1
What is the value of $\alpha\beta\gamma(\alpha + \beta + \gamma)$?
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Answer
To find the value of αβγ(α+β+γ) for the polynomial given, we can use Vieta's formulas, which relate the coefficients of the polynomial to sums and products of its roots.
Identify Roots: From the polynomial 2x3+6x2−7x−10, Vieta's formulas tell us:
The product of the roots (
etaetaeta) = a−d=2−(−10)=5
The sum of the roots (α+β+γ) = a−b=2−6=−3.
Calculate the Expression:
Now substitute these values into the expression:
αβγ(α+β+γ)=5⋅(−3)=−15.
Thus, the required value of αβγ(α+β+γ) is -15.
Given the options in the question, the correct answer is B: -15.