We are given with the equation <span>f(x) = ax3 + bx2 + cx + d
Substituting, (3,11)
</span><span>11= 27a + 9b + 3c + d
</span><span>@(5, 9)
</span><span>9 = 125 a + 25 b + 5c + d
@</span><span>(4, 10)
</span><span>10 = 64 a + 16 b + 4c + d
@inflection point, second derivative is equal to zero
</span><span>f'(x) = 3ax2 + 2bx + c
</span>f''(x) = 6ax + 2b = 0
when x is 4, 24 a + 2b = 0 or 12a + b = 0.
There are 4 equations, 4 unknowns: answer is
<span>0.5 x^3 - 6x^2 + 22.5 - 24 = 0</span>
Answer:
Step-by-step explanation:
![\frac{15}{\sqrt{31} - 4}\\\\=\frac{15}{\sqrt{31} - 4} \times \frac{\sqrt{31} + 4}{\sqrt{31}+ 4} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ [ \ rationalizing \ the \ denominator \ ]\\\\=\frac{15( \sqrt{31} + 4 )}{(\sqrt{31})^2 - (4)^2} \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ [ \ (a-b)(a+b) = a^2 - b^2 \ ]\\\\=\frac{15 ( \sqrt{31} + 4)}{31 - 16}\\\\=\frac{15 (\sqrt{31} + 4)}{15}\\\\= \sqrt{31} + 4](https://tex.z-dn.net/?f=%5Cfrac%7B15%7D%7B%5Csqrt%7B31%7D%20-%204%7D%5C%5C%5C%5C%3D%5Cfrac%7B15%7D%7B%5Csqrt%7B31%7D%20-%204%7D%20%5Ctimes%20%5Cfrac%7B%5Csqrt%7B31%7D%20%2B%204%7D%7B%5Csqrt%7B31%7D%2B%204%7D%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%20%20%5B%20%20%5C%20rationalizing%20%5C%20the%20%5C%20denominator%20%5C%20%5D%5C%5C%5C%5C%3D%5Cfrac%7B15%28%20%5Csqrt%7B31%7D%20%2B%204%20%29%7D%7B%28%5Csqrt%7B31%7D%29%5E2%20-%20%284%29%5E2%7D%20%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%5C%20%20%5C%20%5C%20%5C%20%5B%20%5C%20%28a-b%29%28a%2Bb%29%20%3D%20a%5E2%20-%20b%5E2%20%5C%20%5D%5C%5C%5C%5C%3D%5Cfrac%7B15%20%28%20%5Csqrt%7B31%7D%20%2B%204%29%7D%7B31%20-%2016%7D%5C%5C%5C%5C%3D%5Cfrac%7B15%20%28%5Csqrt%7B31%7D%20%2B%204%29%7D%7B15%7D%5C%5C%5C%5C%3D%20%5Csqrt%7B31%7D%20%2B%204)
Step-by-step explanation:
A = (1/2)bh ---> h = 2A/b = 2(12 cm^2)/(5 cm) = 4.80 cm
---> x^2 = h^2 + (b/2)^2
= (4.8 cm)^2 + (2.5)^2
= 23.04 cm^2 + 6.25 cm^2
or x = 5.41 cm
Therefore, the perimeter P is
P = 2x + b = 2(5.41 cm) + 5 cm = 15.8 cm
