Решите дискриминант.

x^2-5x=14

9+4x^2-12x=0

2x^2-9x-5=0

4x^2=9+16x

3+4x^2-x=0

x^2+x=0

8-2c^2=0

N 1

x^2 - 5x = 14

x^2 - 5x - 14 = 0

D = 25 + 56 = 81 = 9^2

x1 = (5 + 9) : 2 = 7

x2 = (5 - 9) : 2 = - 2

N 2

9 + 4x^2 - 12x = 0

4x^2 - 12x + 9 = 0

D = 144 - 144 = 0

x = 12 : 8 = 1,5

N 3

2x^2 - 9x - 5 = 0

D = 81 + 40 = 121 = 11^2

x1 = (9 + 11) : 4 = 5

x2 = (9 - 11) : 4 = - 0,5

N 4

4x^2 = 9 + 16x

4x^2 - 16x - 9 = 0

D = 256 + 144 = 400 = 20^2

x1 = (16 + 20) : 8 = 4,5

x2 = (16 - 20) : 8 = - 0,5

N 5

3 + 4x^2 - x = 0

4x^2 - x + 3 = 0

D = 1 - 48 = - 47

D < 0; Нет корней

N 6

x^2 + x = 0

x (x + 1) = 0

x1 = 0

x2 = - 1

N 7

8 - 2 с^2 = 0

2 (4 - c^2) = 0

2 (2 - c) (2 + c) = 0

C1 = 2

C2 = - 2