Пусть
Тогда:
8t^2-33t+4 =0
D = 1089 - 4*8*4 = 961 = 31^2
t1=(33+31)/16 = 4
t2=(33-31)/16 = 2/16 = 1/8
x1=2
x2= -3
2) 9^(x+1)-28*3^x+3=0
9*3^(2x) - 28*3^x + 3 = 0
3^x = t
9t^2 -28t+3=0
D = 784 - 4*9*3 = 676 = 26^2
t1 = (28+26)/18 = 3
t2 = (28-26)/18 = 2/18 = 1/9
3^x=3
x1= 1
3^x=1/9
x2 = -2