
Arithmetic Sequence
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.
I'm trying to use the formula: tn= t1+(n1)d but cant figure out where to get the numbers. Please step by step on how to get answer would be really helpful. Thanks

Re: Arithmetic Sequence
Using the given information, we obtain two equations in two unknowns:
$\displaystyle t_1+10d=53$
$\displaystyle (t_1+4d)+(t_1+6d)=56\,\therefore\,2t_1+10d=56$
If we subtract the first equation from the second, we will eliminate $\displaystyle d$ and we can solve for $\displaystyle t_1$. Then we can use this value to find $\displaystyle d$ from either of the original equations.

Re: Arithmetic Sequence

Re: Arithmetic Sequence

Re: Arithmetic Sequence
oh sweet thanks so much! d=5 i got it now. everything fell into place :)

Re: Arithmetic Sequence