Answer:
150
Step-by-step explanation:
3×0=0
3×1=3
3×2=6
3×3=9
....
3×50=150
Let

. Then

and

are two fundamental, linearly independent solution that satisfy


Note that

, so that

. Adding

doesn't change this, since

.
So if we suppose

then substituting

would give

To make sure everything cancels out, multiply the second degree term by

, so that

Then if

, we get

as desired. So one possible ODE would be

(See "Euler-Cauchy equation" for more info)
Answer:
35 ways
Step-by-step explanation:
Alex has 9 friends and wants to invite 5 friends. Since Alex requires two of his friends who are twins to come together to his birthday party, since the two of them form a group, the number of ways we can select the two of them to form a group of two is ²C₂ = 1 way.
Since we have removed two out of the nine friends, we are left with 7 friends. Also, two friends are already selected, so we are left with space for 3 friends. So, the number of ways we can select a group of 3 friends out of 7 is ⁷C₃ = 7 × 6 × 5/3! = 35 ways.
So, the total number ways we can select 5 friend out of 9 to party come to the birthday include two friends is ²C₂ × ⁷C₃ = 1 × 35 = 35 ways
Answer:
d = 8/9
Step-by-step explanation:
All you have to do is add 5/9 to both sides.
d - 5/9 + 5/9 = 3/9 + 5/9
d = 89
So, d = 8/9.