Level:
Project ID:
1003057906
Accepted:
1
Clonable:
0
Easy:
1
The sum of the first \( 15 \) terms of an arithmetic sequence is \( 210 \) and the \( 15 \)th term is \( 7 \). Choose the correct formula of calculation of the first term.
\( a_1=\frac2{15}\cdot210-7 \)
\( a_1=\frac2{15}\cdot\frac{210}7 \)
\( a_1=\frac{15}2\cdot210-7 \)
\( a_1= \frac{210}7 \)
\( a_1=\frac2{15} (210-7) \)