Question

Determine o 1° termo sendo a30= -17/2 e r= 1/4

Answer 1

$an = a1 + ( n -1) . r \\ \\ \\ -\dfrac{17}{2} = a1 + ( 30 -1) . \dfrac{1}{4}\\ \\ \\ -\dfrac{17}{2} = a1 + (29) . \dfrac{1}{4} \\ \\ \\ -\dfrac{17}{2} = a1 + \dfrac{29}{4}\\ \\ \\-\dfrac{17}{2} - \dfrac{29}{4} = a1\\ \\ \\ a1 = -\dfrac{63}{4}$