### Home > CCA > Chapter 5 > Lesson 5.3.3 > Problem5-122

5-122.

An arithmetic sequence has$t(8)=1056$ and $t(13)=116$. Write an equation for the sequence. What is $t(5)$? Homework Help ✎

The general equation for an aritmetic sequence is t(n) = mn + b.

Use t(8) = 1056 to write an equation.
t(8) = m(8) + b or 1056 = 8m + b

Use t(13) = 116 to write another equation.

Solve the system of equations you wrote for m and b.

t(n) = −188n + 2560

To find t(5), substitute 5 for n in the equation that you wrote.