Mathematics
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OpenStudy (anonymous):
50th term is 238, 93rd term is 539. state the general term
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hartnn (hartnn):
of AP?
OpenStudy (anonymous):
what?
hartnn (hartnn):
of Arithmetic sequence ??
hartnn (hartnn):
general term of what?
OpenStudy (anonymous):
yes arithmetic
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hartnn (hartnn):
the general 'n' term is
\[T_n=a+((n-1)d)\]
so T50=238=a+49d ----->(1)
T93=539=a+92d ----->(2)
can u solve these two equations to get a and d ??
hartnn (hartnn):
u can start by subtracting (1) from (2)
OpenStudy (anonymous):
so a=49d-a+92d ?
OpenStudy (anonymous):
*a+49d-a+92d ?
hartnn (hartnn):
yes,thats your right side,where a gets cancelled
but whats your left side??
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hartnn (hartnn):
and *92d-49d
OpenStudy (anonymous):
oh, so um im not sure
hartnn (hartnn):
ok,subtracting the equations u get
539-238=(92-49)d
so
\[d=\frac{539-238}{92-49}=??\]
OpenStudy (anonymous):
258?
hartnn (hartnn):
how 258?
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OpenStudy (anonymous):
because I got 301/43 = 258?
hartnn (hartnn):
301/43 is actually only 7
OpenStudy (anonymous):
oh worry yeah I got 7
hartnn (hartnn):
so u have d=7
now can put d=7 in any equation and find the value of a
hartnn (hartnn):
238=a+49*7
a=343-238=??
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OpenStudy (anonymous):
105?
hartnn (hartnn):
yup :)
so u have a=105,d=7
and your general term will be :
\[T_n=105+7(n-1)\]
hartnn (hartnn):
yup :)
so u have a=105,d=7
and your general term will be :
\[T_n=105+7(n-1)\]
OpenStudy (anonymous):
no the answer should be tn=7n-112
OpenStudy (anonymous):
but i dont know how to get that
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hartnn (hartnn):
oh,sorry
a would be -105
so
\[T_n=-105+7(n-1)=-105+7n-7=7n-112\]
ok ?
OpenStudy (anonymous):
thank you :)