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32 votes
32 votes
If x=-1/2 is a zero of the polynomial p(x)=8x^3-ax^2-x+2, find the value of a.

User Ghulam Moinul Quadir
by
2.9k points

1 Answer

17 votes
17 votes

If
x=-\frac12 is a zero, then
p\left(-\frac12\right) = 0. Solve this equation for
a.


p\left(-\frac12\right) = 8\left(-\frac12\right)^3 - a\left(-\frac12\right)^2 - \left(-\frac12\right) + 2 = 0


-1 - \frac a4 + \frac12 + 2 = 0


-\frac a4 = -\frac32


\boxed{a = 6}

User ZiMtyth
by
2.4k points
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