yes even more random problems

[Salvadoramerican]

another 3 problems, i need to put dates on these

1. If a1=-3, a2=4, and a3=11, then ax=536. Find x. ans 78
-i think the formula is a(x-2)x5+a(x-1)x4=ax from what i have so far

2 The sum of the three geometric mean between 3 and 48 is? ans 42

3. 10 girls and 7 boys sign up to participate on an academic team. Each team consists of 5 members. How many different teams can be formed if at least 3 of the members are girls.

[nsguy1350]

1. It's just an arithmetic sequence... add 7 every time.
Think of it as a function. It's a line, and since it increases by 7 each time, you could say the slope is 7. Since the first term is -3, instead of 7, which the function 7x would be at x = 1, you can say this is the function 7x - 10. Solve for when this is equal to 536.
7x - 10 = 536
7x = 546
x = 78.

2. I'm not sure what this is asking, and it can's be asking for the sum of the AM, the GM, and the HM either.

3.Case work:
Case 1: 3 girls, 2 boys
Case 2: 4 girls, 1 boy
Case 3: 5 girls, 0 boys
Find the number of combinations for each and add.