To find the value of k such that the polynomial x² + kx + 6x² + 2kx + 1 has the sum of its zeroes equal to half of their product, we start by rewriting the polynomial in its standard form.
First, combine like terms:
x² + 6x² + kx + 2kx + 1 = (7x²) + (k + 2k)x + 1 = 7x² + (3k)x + 1
Now, we can denote the polynomial as:
f(x) = 7x² + 3kx + 1
According to Vieta’s formulas for a quadratic polynomial ax² + bx + c, the sum of the roots (α + β) is given by:
-(b/a) = -(3k/7)
And the product of the roots (αβ) is given by:
c/a = (1/7)
According to the problem, we are looking for the case where the sum of the roots equals half of their product:
-(3k/7) = 1/2 * (1/7)
Now, simplifying this equation:
-(3k/7) = 1/14
Multiplying both sides by -7 gives:
3k = -1/2
Now, dividing both sides by 3, we find:
k = -1/6
Thus, the value of k such that the polynomial has the sum of its zeroes equal to half of their product is -1/6.