Question

faceti problema 2, va rog, nu-mi vine rezolvarea

Answer 1

2)

1 + 3 + 5 + ......+ (2x -1) = 100

aflam cati termeni are S = > (2x - 1 + 1)/2 = 2x/2 = x (termeni)

(1 + 2x - 1) × x / 2 = 100

2x × x / 2 = 100

x² = 100

x = √100 = 10

2x - 1 = 2 × 10 - 1 = 19 ( ultimul termen al sirului )

1 + 3 + 5 + ....+ 19 = 100

Answer 2

am anexat rezolvarea ptr. probl. 2)

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