Answer:
168
Step-by-step explanation:
2x80 is 160 plus 2x4 is 8 160+8 is 168
By letting
![y = \displaystyle \sum_{n=0}^\infty c_n x^{n+r}](https://tex.z-dn.net/?f=y%20%3D%20%5Cdisplaystyle%20%5Csum_%7Bn%3D0%7D%5E%5Cinfty%20c_n%20x%5E%7Bn%2Br%7D)
we get derivatives
![y' = \displaystyle \sum_{n=0}^\infty (n+r) c_n x^{n+r-1}](https://tex.z-dn.net/?f=y%27%20%3D%20%5Cdisplaystyle%20%5Csum_%7Bn%3D0%7D%5E%5Cinfty%20%28n%2Br%29%20c_n%20x%5E%7Bn%2Br-1%7D)
![y'' = \displaystyle \sum_{n=0}^\infty (n+r) (n+r-1) c_n x^{n+r-2}](https://tex.z-dn.net/?f=y%27%27%20%3D%20%5Cdisplaystyle%20%5Csum_%7Bn%3D0%7D%5E%5Cinfty%20%28n%2Br%29%20%28n%2Br-1%29%20c_n%20x%5E%7Bn%2Br-2%7D)
a) Substitute these into the differential equation. After a lot of simplification, the equation reduces to
![5r(r-1) c_0 x^{r-1} + \displaystyle \sum_{n=1}^\infty \bigg( (n+r+1) c_n + (n + r + 1) (5n + 5r + 1) c_{n+1} \bigg) x^{n+r} = 0](https://tex.z-dn.net/?f=5r%28r-1%29%20c_0%20x%5E%7Br-1%7D%20%2B%20%5Cdisplaystyle%20%5Csum_%7Bn%3D1%7D%5E%5Cinfty%20%5Cbigg%28%20%28n%2Br%2B1%29%20c_n%20%2B%20%28n%20%2B%20r%20%2B%201%29%20%285n%20%2B%205r%20%2B%201%29%20c_%7Bn%2B1%7D%20%5Cbigg%29%20x%5E%7Bn%2Br%7D%20%3D%200)
Examine the lowest degree term
, which gives rise to the indicial equation,
![5r (r - 1) + r = 0 \implies 5r^2 - 4r = r (5r - 4) = 0](https://tex.z-dn.net/?f=5r%20%28r%20-%201%29%20%2B%20r%20%3D%200%20%5Cimplies%205r%5E2%20-%204r%20%3D%20r%20%285r%20-%204%29%20%3D%200)
with roots at r = 0 and r = 4/5.
b) The recurrence for the coefficients
is
![(k+r+1) c_k + (k + r + 1) (5k + 5r + 1) c_{k+1} = 0 \implies c_{k+1} = -\dfrac{c_k}{5k+5r+1}](https://tex.z-dn.net/?f=%28k%2Br%2B1%29%20c_k%20%2B%20%28k%20%2B%20r%20%2B%201%29%20%285k%20%2B%205r%20%2B%201%29%20c_%7Bk%2B1%7D%20%3D%200%20%5Cimplies%20c_%7Bk%2B1%7D%20%3D%20-%5Cdfrac%7Bc_k%7D%7B5k%2B5r%2B1%7D)
so that with r = 4/5, the coefficients are governed by
![c_{k+1} = -\dfrac{c_k}{5k+5} \implies \boxed{g(k) = -\dfrac1{5k+5}}](https://tex.z-dn.net/?f=c_%7Bk%2B1%7D%20%3D%20-%5Cdfrac%7Bc_k%7D%7B5k%2B5%7D%20%5Cimplies%20%5Cboxed%7Bg%28k%29%20%3D%20-%5Cdfrac1%7B5k%2B5%7D%7D)
c) Starting with
, we find
![c_1 = -\dfrac{c_0}5 = -\dfrac15](https://tex.z-dn.net/?f=c_1%20%3D%20-%5Cdfrac%7Bc_0%7D5%20%3D%20-%5Cdfrac15)
![c_2 = -\dfrac{c_1}{10} = \dfrac1{50}](https://tex.z-dn.net/?f=c_2%20%3D%20-%5Cdfrac%7Bc_1%7D%7B10%7D%20%3D%20%5Cdfrac1%7B50%7D)
so that the first three terms of the solution are
![\displaystyle \sum_{n=0}^2 c_n x^{n + 4/5} = \boxed{x^{4/5} - \dfrac15 x^{9/5} + \frac1{50} x^{13/5}}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Csum_%7Bn%3D0%7D%5E2%20c_n%20x%5E%7Bn%20%2B%204%2F5%7D%20%3D%20%5Cboxed%7Bx%5E%7B4%2F5%7D%20-%20%5Cdfrac15%20x%5E%7B9%2F5%7D%20%2B%20%5Cfrac1%7B50%7D%20x%5E%7B13%2F5%7D%7D)
Answer:
B. 6
Step-by-step explanation:
D. 12 cant be multiplied to get 18
C. 4 cant be multiplied to get 18
A. 2 is a common factor of 12 and 18 but not the greatest.
B. 6 times 2 is 12 and 6 times 3 is 18 so 6 is the greatest common factor.
Answer:
x^3 +8x^2 +13
Step-by-step explanation:
(6x^2 - 3 + 5x^3) - (4x^3 - 2x^2 - 16)
Distribute the minus sign
6x^2 - 3 + 5x^3 -4x^3 + 2x^2 + 16
Combine like terms
x^3 +8x^2 +13
Answer is C please give brainliest