Asked by Cherish

The third and seventh terms of an ap are respectively -2 and 10 find the value of the first term and number of term which must be add to give sum of 410
Answered by Cherish
Where is the answer
Answered by Cherish
Where is the working
Answered by Goodness
Am asking the same question
Answered by Anonymous
Tn = a + (n-1) d
so for example T3 = a + 2 d and T7 = a + 6 d
that gives you two linear equations to solve for a and d
then use the equation for sum of terms to find the n for sum of 410
Answered by Anonymous
If you do not understand what I said, Google:
Math is Fun arithmetic sequence
Answered by Anonymous
I am not about to do it for you. It is pure plug and chug.
Answered by oobleck
a+2d = -2
a+6d = 10
solve for a and d, and then you have
n/2 (2a+(n-1)d) = 410
Since you now know a and d, just use them to solve for n
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