Question 1188493: The 20th term is 26 and the common difference is -5. Find the 1st term and 15th term. Found 2 solutions by ikleyn, MathTherapy:Answer by ikleyn(52802) (Show Source):
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The 20th term is 26 and the common difference is -5. Find the 1st term and 15th term.
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= + (20-1)*d
26 = + 19*(-5)
26 - 19*(-5) =
26 + 95 = = 121. <<<---=== the 1-st term
= + (15-1)*(-5)
= 121 + 14*(-5) = 121 - 70 = 51. <<<---=== .
ANSWER. 1-st term is 121. 15-th therm is 51.
