Sequence

The arithmetic sequence is given:

Sn=1656, d=6, an=138

Calculate a1 and n.

Correct answer:

a =  0
n =  24

Step-by-step explanation:

s=1656 d=6 b=138  b = a + d (n1) s = n (a+b)/2  a = b  d (n1) 2s = n (a+b)  2s = n (b  d (n1)+b)  2 1656=n (2 1386 (n1))  2 1656=n (2 1386 (n1)) 6n2282n+3312=0 6=23 282=2347 3312=243223 GCD(6,282,3312)=23=6  n247n+552=0  a=1;b=47;c=552 D=b24ac=47241552=1 D>0  n1,2=2ab±D=247±1 n1,2=247±1 n1,2=23.5±0.5 n1=24 n2=23  n>0 n=n1=24 a=bd (n1)=1386 (241)=0

Our quadratic equation calculator calculates it.

n=n1=24



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