Question

S7=26см.найти s2 и s9

Answer 1

S=26:7
s=3.7
s2=3.7*2=7.4
s9=3.7*9=33.3

Answer 2

It seems like you are trying to find the sum of an arithmetic sequence. In order to find the values of S2 (sum of the first two terms) and S9 (sum of the first nine terms), we first need to know the formula for the sum of an arithmetic sequence.

The formula to find the sum of an arithmetic sequence is:

Sn = n/2 * (a + l)

Where:

• Sn is the sum of the first n terms of the sequence.
• n is the number of terms.
• a is the first term of the sequence.
• l is the last term of the sequence.

In your case, you provided the first term (a) as S7 = 26 cm. However, we need more information to proceed. We either need the value of the common difference (d) between the terms, or we need the last term (l) of the sequence to calculate the sums S2 and S9.

If you have the value of the common difference (d) or the last term (l), please provide that information so I can assist you further in calculating S2 and S9.