46/10 ÷ (5/3-32/10)+11/8=46/10 ÷ (50-96)/30 +11/8= 46/10 ÷(-46/30) +11/8= 46/10 × (-30/46) + 11/8= -3+11/8= (-24+11)/8= -13/8
1)a1=11 a2=21⇒d=a2-a1=21-11=10
an=11+10(n-1)=11+10n-10=10n+1
2)10n+1≤150
10n≤149
n≤14,9
n=14
3)S14=(2a1+13d)*14/2=(22+130)*7=152*7=1064
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