Question

1) х + 9√х + 14 = 0.
2)9х⁴ - 19х² + 2 = 0
3)





8 класс

Answer 1

1) √x=t, t≥0

t²+9t+14=0

D=81-56= 25

t1= (-9-5)/2= -7 - не корень

t2= (-9+5)/2= -2 - не корень

корней нет.

2) x²=t, t≥0

9t²-19t+2=0

D= 361-72= 289

t1= (19-17)/18= 1/9

t2= (19+17)/18= 2

x1= -1/3

x2= 1/3

x3= -√2

x4= √2

3) x≠-8

2x²-13x+6=0

D= 169- 48= 121

x1= (13-11)/4= 0,5

x2= (13+11)/4= 6