## College Algebra (6th Edition)

Descartes's Rule of Signs (page 384) Let $f(x)=a_{n}x^{n}+a_{n-1}x^{n-1}+\cdots+a_{2}x^{2}+a_{1}x+a_{0}$ be a polynomial with real coefficients. 1. The number of positive real zeros of $f$ is either $\mathrm{a}$. the same as the number of sign changes of $f(x)$ or $\mathrm{b}$. less than the number of sign changes of $f(x)$ by a positive even integer. If $f(x)$ has only one variation in sign, then $f$ has exactly one positive real zero. 2. The number of NEGATIVE ... --------------------------- With 7 sign changes the number of positive zeros can be (a) $7$ or (b) $7-2=5$ or $7-4=3$ or $7-6 = 1$ True