X⁴ - 13x² + 36 = 0
Замена переменной t = x²
t² - 13t + 36 = 0
D = (- 13)² - 4 × 36 = 169 - 144 = 25
t₁ =
=
= 4
t₂ =
=
= 9
x²₁ = 4
x²₂ = 9
x₁ =
= +-2
x₂ =
= +-3
Ответ: +-2; +-3
2,5х - 6,3 = 7 1/3
2,5х - 6,3 = 22/3
2,5х = 22/3 + 6,3 = 22/3 + 63/10
2,5х = 220/30 +189/30 = 409/30
25/10 х = 409/30
75/30 х = 409/30
х = 409/30 / 75/30 = 409/30 * 30/75 = 409/75 = 5 34/75
х равен 5 34/75 или 5,45
5^х + 5^ х-1 =6
5^х( 1 +1/5)=6
6/5 *5^х=6
5^х = 6 :6/5
5^х= 5
Х=1
12:2=6 длина bc
12+6+18=36 длина ломаной