Pertanyaan

Hitunglah U n dan S n pada deret geometri berikut − 2 1 , 10 3 , − 50 9 , ... ( n = 5 )

Hitunglah $U_{n}$ dan $S_{n}$ pada deret geometri berikut

$- \frac{1}{2}$ , $\frac{3}{10}$ , $- \frac{9}{50}$ , ... $(n = 5)$

N. Mustikowati

Master Teacher

Mahasiswa/Alumni Universitas Negeri Jakarta

Jawaban terverifikasi

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$begin mathsize 14px style a equals negative 1 half comma space r equals negative 3 over 5 U subscript 5 equals a r to the power of 4 equals open parentheses negative 1 half close parentheses open parentheses negative 3 over 5 close parentheses to the power of 4 U subscript 5 equals negative fraction numerator 81 over denominator 1.250 end fraction S subscript 5 equals fraction numerator a open parentheses 1 minus r to the power of n close parentheses over denominator 1 minus r end fraction equals fraction numerator open parentheses negative begin display style 1 half end style close parentheses open parentheses 1 minus open parentheses negative begin display style 3 over 5 end style close parentheses to the power of 5 close parentheses over denominator 1 minus open parentheses negative begin display style 3 over 5 end style close parentheses end fraction S subscript 5 equals fraction numerator open parentheses negative begin display style 1 half end style close parentheses open parentheses 1 plus begin display style fraction numerator 243 over denominator 3.125 end fraction end style close parentheses over denominator 1 plus begin display style 3 over 5 end style end fraction S subscript 5 equals fraction numerator open parentheses negative begin display style fraction numerator 1.684 over denominator 3.125 end fraction end style close parentheses over denominator begin display style 8 over 5 end style end fraction equals open parentheses negative fraction numerator 1.684 over denominator 3.125 end fraction close parentheses times open parentheses 5 over 8 close parentheses S subscript 5 equals negative fraction numerator 421 over denominator 1.250 end fraction end style$