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What is the first term if t2=-12 and t5 =9 ( arithmetic)
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High School Teacher
To solve, apply the formula of finding the nth term of an arithmetic sequence which is:
`T_n=T_1 + (n-1)d`
where Tn is the nth term, T1 is the first term, and d is the common difference.
Since the T2=-12, then:
`-12=T_1+d` (Let this be EQ1)
Also, since T5=9, then:
`9=T_1+4d` (Let this be EQ2)
Next, use these two equations to solve for the first term T1.
To do so, multiply EQ1 by 4.
Then, subtract this from EQ2.
Then, divide both sides by -3.
Hence, the first term is -19.
Posted by mjripalda on June 14, 2013 at 3:30 AM (Answer #1)
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