Odpowiedź:
Szczegółowe wyjaśnienie:
1)
a1 = 4 + 3 = 7
a2 = 4*2 + 3 = 11
a3 = 4*3 + 3 = 15
a4 = 4*4 + 3 = 19
r = a2 - a1 = 4
2)
[tex]\frac{(x-2)+(x+6)}{2} = 3\\\frac{2x +4}{2} = 3\\x+ 2 = 3\\x = 1\\[/tex]
3) r = 16 - 8 = 8
a1 = 8
an = 8 + (n-1) * 8 = 8n
[tex]S_{1-20} = \frac{(a_1 + a_{20})n}{2}[/tex]
[tex]a_{20} = 8 *20 = 160\\[/tex]
[tex]S_{1-20} = \frac{(8+160)*20}{2} = 1680[/tex]
4)
r = a2 - a1 = 15 - 10 = 5
a1 = 10
an = 10 + 5*(n-1)
150 = 10 + 5(n-1)
140 = 5(n-1)
28 = n - 1
n = 29
[tex]S = \frac{(10+150)*29}{2} = 2320[/tex]
