How is the common difference of an arithmetic sequence obtained?
By choosing any term after the first and subtracting the preceding term from it.
By choosing any term after the first and adding the subsequent term to it.
By choosing any term after the first and dividing it by the preceding term.
By choosing any term after the first and adding the preceding term to it.
Find the sum of the first $10$10 terms of the arithmetic sequence defined by $a=6$a=6 and $d=3$d=3.
Find the sum of the first $10$10 terms of the arithmetic sequence defined by $a=-18$a=−18 and $d=4$d=4.
Find the sum of the first $15$15 terms in the arithmetic sequence $2+6+10$2+6+10 $+$+ ...