Jawaban:

6,045

Penjelasan:

Deret -2,011 + (-2,009) + (-2,007) +..... + 2,011 + 2,013 + 2,015 + 2,017

Suku pertama (a) = (-2,011)

Suku terakhir (Un) = 2,017

Beda (b) = (-2,009) - (-2,011)

= -2,009 + 2,011

b = 2

Menentukan banyak suku

Un = a + (n - 1) b

2,017 = (-2,011) + (n - 1) 2

2,017 = (-2,011) + 2n - 2

2,017 = (-2,013) + 2n

2,017 + 2,013 = 2n

4,030 = 2n

n = \displaystyle \frac{4,030}{2}

2

4,030

n = 2,015

Menentukan jumlah barisan

Sn = \displaystyle \frac{n}{2}

2

n

(a + Un)

S₂₀₁₅ = \displaystyle \frac{2015}{2}

2

2015

(-2,011 + 2,017)

= \displaystyle \frac{2015}{2}

2

2015

× 6

= 2015 × 3

= 6,045

Jadi nilai dari -2,011 + (-2,009) + (-2,007) +..... + 2,011 + 2,013 + 2,015 + 2,017 adalah 6,045