SOLUTION: Hi everyone i hope someone can help me . im using the
{{{ Sn= (n/2) (2a +(n-1)d) }}} formula with a=first term and d= common difference
im trying to solve for a if S21=315
Algebra.Com
Question 357859: Hi everyone i hope someone can help me . im using the
formula with a=first term and d= common difference
im trying to solve for a if S21=315 and d=3 .im a little confused what to do when i get
so i need to solve for a
?? this is where i get my problem. how do i get a on its own??
Iv tried
im not sure from here?? do i just subtract 651 from both sides to find a. im not sure that answer dose not look right.?? any help would be appreciated :)
Found 2 solutions by mobosecomin, mananth:
Answer by mobosecomin(1) (Show Source): You can put this solution on YOUR website!
ok so i solved this myself it was just a silly order of precedence problem i was having
when i got
i should have
multiply everything in the brackets by 10.5
:)
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
so i need to solve for a
multiply by (2/21) on both sides
-30=2a
a=-15
...
m.ananth@hotmail.ca
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