Speedo

The 23rd term in a certain geometric sequence is 16 and the 28th term in the sequence is 24. What is the 43rd term? What is the answer?

A certain 300-term geometric sequence has first term 1337 and common ratio -1/2. How many terms of this sequence are greater than 1?

Let a_1, a_2, . . . , a_10 be an arithmetic sequence. If a_1 + a_3 + a_5 + a_7 + a_9 = 17 and a_2 + a_4 + a_6 + a_8 + a_{10} = 15, then find a_1.

A certain infinite geometric series has first term 7 and sum 4. What is the result when the third term is divided by the second term?

In the top row of an 8*8 chessboard, Tom writes the values 1, 2, 4, 8, 16, 32, 64, 128. In the leftmost column, Tom writes the values 1, 3, 9, 27, 81, 243, 729, 2187. In every other square that doesn't have a number yet, Tom writes the product of the left...

Alpha writes the infinite arithmetic sequence 10, 8, 6, 4, 2, 0... Beta writes the infinite geometric sequence 9, 6, 4, 8/3, 16/9,... Gamma makes a sequence whose n^th term is the product of the n^th term of Alpha's sequence and the n^th term of Beta's se...

Suppose that ab = 7 and a^2b + ab^2 + a+b = 80. What is a^2+b^2?

Find the ordered quintuplet (a,b,c,d,e) that satisfies the system of equations a+2b+3c+4d+5e=177, 2a+3b+4c+5d+e=154, 3a+4b+5c+d+2e=146, 4a+5b+c+2d+3e=138, 5a+b+2c+3d+4e=165 This a really hard questioon but don't give up, please.

The sequence x_1, x_2, x_3, . . ., has the property that x_n = x_{n - 1} + x_{n - 2} for all n>=3. If x_{11} - x_1 = 99, then determine x_6.

The sequence x_1, x_2, x_3, . . ., has the property that x_n = x_{n - 1} + x_{n - 2} for all n \ge 3. If x_{11} - x_1 = 99, then determine x_6. Steve, you made a mistake for x_4.

There are 5 boys and 4 girls in my class. In how many ways can they be seated in a row of 9 chairs such that at least 2 boys are next to each other? In how many ways can they be seated in a row of 9 chairs such that at least 3 girls are all next to each o...

There are 5 boys and 4 girls in my class. In how many ways can they be seated in a row of 9 chairs such that at least 3 girls are all next to each other?

In how many ways can you spell the word COOL in the grid below? You can start on any letter, then on each step you can step one letter in any direction (up, down, left, right, or diagonal). You cannot visit the same letter twice. C C C C C L O O O L L O O...

Thanks, guys!

This is what you did wrong, i think. YOu multiply not add.

19

everything got confusing after that

no reply

sorry, i mean you are correct? but how about number 2. That was harder for me.

the question mark is a ! not a ?

I tried like 10 different answers and they were all wrong.

could be 5 or 7