# Arithmetic Sequence

1. Nov 16, 2012

### Vince604

1. The problem statement, all variables and given/known data
In an arithmetic sequence, the 11th term is 53 and the sum ofof the 5th and 7th terms is 56. Find the first 3 terms of the sequence.

2. Relevant equations

3. The attempt at a solution

I'm trying to use the formula: tn= t1+(n-1)d but dont have right numbers. please show me step by step would be really helpful. Thanks

2. Nov 16, 2012

### ehild

What is the 11th term of the sequence, in terms of t1 and d?
What are the 5th and 7th terms?

ehild

3. Nov 16, 2012

### symbolipoint

This problem description has two unknown values which need to be solved. You can find a system of equations using information about the 11th term and the relationship between the 5th and 7th terms. Your unknown numbers to solve for first are d and t1.

The relevant equation for part 2 of the homework template is tn=t1+(n-1)d

4. Nov 17, 2012

### Bonaparte

I'll give you an even bigger hint than Symbol and ehild gave:
a(n) = a1 + (n-1)d
substitute 11....
53 = a1+10d
you can do the rest ;)

Thanks and good luck, Bonaparte

5. Nov 17, 2012

### Staff: Mentor

From the PF rules:
In other words, we don't provide step-by-step solutions. We'll help you with the work you do.

6. Nov 17, 2012

okay thanks