I need help again. I'm stuck on something.
If, in an Arithmetic Progression, U5 (5 term) =-.05 and the sum of the first 7 terms = 21, how can we find the first term?
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I need help again. I'm stuck on something.
If, in an Arithmetic Progression, U5 (5 term) =-.05 and the sum of the first 7 terms = 21, how can we find the first term?
Nth term: $\displaystyle U_n = a+(n-1)d$
Sum of n terms: $\displaystyle S_n = \dfrac{n}{2}(2a+(n-1)d)$
Plug in what you know and solve for a
