Find the indicated term of the arithmetic sequence.
-Given an arithmetic sequence with d $$\mathrm { d } = - 6 \text { and } \mathrm { a } _ { 4 } = 10$$ find a20.
A)86
B)-86
C)-92
D)92

Question

Quizplus · Accepted Answer

The formula for the nth term of an arithmetic sequence is $a_n = a_1 + (n - 1)d$. Given $a_4 = 10$ and $d = -6$, we can find $a_1$ by substituting $n = 4$ into the formula: $10 = a_1 + 3(-6)$, which simplifies to $10 = a_1 - 18$, so $a_1 = 28$. To find $a_{20}$, substitute $n = 20$, $a_1 = 28$, and $d = -6$ into the formula: $a_{20} = 28 + (20 - 1)(-6) = 28 - 114 = -86$.

Find the Indicated Term of the Arithmetic Sequence d=−6 and a4=10\mathrm { d } = - 6 \text { and } \mathrm { a } _ { 4 } = 10d=−6 and a4​=10

Find the Indicated Term of the Arithmetic Sequence $\mathrm { d } = - 6 \text { and } \mathrm { a } _ { 4 } = 10$