(3x−20)^2 −5(3x−20)+6=0

Question

(3x−20)^2 −5(3x−20)+6=0

Answer 1

(3x−20)² −5(3x−20)+6=0,

пусть 3х-20 = а, тогда:

а² - 5а + 6 = 0,
Д = (-5)² - 4 * 1 * 6 = 25 - 24 = 1,
а1 = (5+1)/2*1 = 6/2 = 3,
а2 = (5 - 1)/2*1 = 2/2 = 2,

при а1=3:
3х-20 = 3,
3х = 23,
х1 = 7 2/3,

при а2=2:
3х-20=2,
3х = 22,
х2 = 7 1/3