Answer:
532
Step-by-step explanation:
Sum of the first n terms of an arithmetic series:
[tex]\boxed{S_n=\dfrac{n}{2}(a_1+a_n)}[/tex]
Where:
- aₙ is the nth term.
- a₁ is the first term.
- n is the position of the term.
Given terms:
- [tex]a_1=12[/tex]
- [tex]a_n=64[/tex]
Substitute the given terms into the formula to create an equation for the nth term:
[tex]\implies S_n=\dfrac{n}{2}(12+64)[/tex]
[tex]\implies S_n=\dfrac{n}{2}(76)[/tex]
[tex]\implies S_n=38n[/tex]
To find S₁₄, substitute n = 14 into the found equation:
[tex]\begin{aligned}n=14 \implies S_{14}&=38(14)\\ & = 532\end{aligned}[/tex]
