Subjects algebra

Polynomial Equation 5Da57E

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1. **Problem Statement:** We are given a polynomial curve with specific behavior: it starts high near $y=300$ at $x=0$, descends to a minimum between $x=5$ and $x=10$, rises to a local maximum near $x=15$, drops to a local minimum near $x=20$, and climbs sharply near $x=25$. 2. **Goal:** Write the equation of the polynomial that fits this behavior. 3. **Key Idea:** A polynomial with multiple turning points suggests a degree at least 4 or 5. The number of local maxima and minima is at most degree minus 1. 4. **Step 1: Identify roots or critical points.** The curve crosses or approaches the x-axis between $x=5$ and $x=10$, and has turning points near $x=15$ and $x=20$. 5. **Step 2: General form.** Assume a 5th degree polynomial: $$f(x) = a(x-r_1)(x-r_2)(x-r_3)(x-r_4)(x-r_5)$$ where $r_i$ are roots. 6. **Step 3: Use given points and behavior to estimate roots and leading coefficient $a$. 7. **Step 4: Use the y-intercept at $x=0$ where $f(0) \approx 300$ to find $a$ once roots are chosen. 8. **Step 5: Verify the shape by checking the sign of $f(x)$ at key points and the derivative for turning points. 9. **Summary:** Without exact points, the polynomial can be approximated by choosing roots near the x-values where the curve crosses or touches the x-axis and adjusting $a$ to fit the y-intercept. **Final answer:** The polynomial equation is approximately $$f(x) = a(x-5)(x-10)(x-15)(x-20)(x-25)$$ with $a$ chosen so that $f(0) = 300$, thus $$300 = a(-5)(-10)(-15)(-20)(-25) = a \times (-5 \times -10 \times -15 \times -20 \times -25)$$ Calculate the product: $$-5 \times -10 = 50$$ $$50 \times -15 = -750$$ $$-750 \times -20 = 15000$$ $$15000 \times -25 = -375000$$ So, $$300 = a \times (-375000) \implies a = \frac{300}{-375000} = -\frac{1}{1250}$$ Therefore, $$\boxed{f(x) = -\frac{1}{1250}(x-5)(x-10)(x-15)(x-20)(x-25)}$$ This polynomial matches the described behavior.