4х² - 1\144=0
(2х - 1\12) (2х + 1\12) = 0
2х - 1\12 = 0; 2х = 1\12; х = 1\24
2х + 1\12 = 0; 2х = -1\12; х=-1\24.
х² + 4х - 180 = 0
Д = 4² - 4 * 1 * (-180) = 16 + 720 = 736
√Д = √736 = 4√46
х1 = (-4 + 4√36)/2 = -4(1 - √36) / 2 = -2(1 - √36) = -2 + 2√36
х2 = -2 - 2√36
А1=7*1-2=5
а2=7*2-2=12
а3=7*3-2=19
а4=7*4-2=26
а10=7*10-2=68