помогите решить срочно
Ответы
Формулы:
D = b^2 - 4ac
x1 = - b - √D / 2a
x2 = - b + √D / 2a
№26.
x^2+ 3x + 2 = 0
a = 1
b = 3
c = 2
D = 3^2 - 4 × 1× 2 = 9 - 8 = 1 D > 0
x1 = - 3 - √1 / 2 × 1 = - 3 - 1 / 2 = - 4
x2 = - 3 + 1 / 2 = - 2 / 2 = - 1
Ответ: - 2 ; -1.
№27.
x^2 + 4x + 3 = 0
a = 1
b = 4
c = 3
D = 4^2 - 4 × 1 × 3 = 16 - 12 = 4 D > 0
x1 = - 4 - √4 / 2 × 1 = - 4 - 2 / 2 = -6 / 2 = - 3
x2 = - 4 + 2 / 2 = -2 / 2 = - 1
Ответ: - 3 ; - 1.
№28.
x^2 + 5x + 4 = 0
a = 1
b = 5
c = 4
D = 5^2 - 4 × 1 × 4 = 25 - 16 = 9 D > 0
x1 = - 5 - √9 / 2 = - 5 - 3 / 2 = - 8 / 2 = - 4
x2 = - 5 + 3 / 2 = - 2 / 2 = - 1
Ответ: - 4 ; - 1.
№29.
x^2 + 6x + 5 = 0
a = 1
b = 6
c = 5
D = 6^2 - 4 × 1 × 5 = 36 - 20 = 16 D > 0
x1 = - 6 - 4 / 2 = - 10 / 2 = - 5
x2 = - 6 + 4 / 2 = - 2 / 2 = - 1
Ответ: - 5 ; - 1.
№30.
x^2 + 10x + 9 = 0
a = 1
b = 10
c = 9
D = 10^2 - 4 × 1 × 9 = 100 - 36 = 64 D > 0
x1 = - 10 - 8 / 2 = - 18 / 2 = - 9
x2 = - 10 + 8 / 2 = - 2 / 2 = - 1
Ответ: - 9 ; - 1.
№31.
x^2 + 16x + 15 = 0
a = 1
b = 16
c = 15
D = 16^2 - 4 × 1 × 15 = 256 - 60 = 196
x1 = - 16 - √196 / 2 = - 16 - 14 / 2 = - 30 / 2 = - 15
x2 = - 16 + 14 / 2 = - 2 / 2 = - 1
Ответ: - 15 ; - 1.
№32.
x^2 + 8x + 15 = 0
a = 1
b = 8
c = 15
D = 8^2 - 4 × 1 × 15 = 64 - 60 = 4
x1 = - 8 - 2 / 2 = - 10 / 2 = - 5
x2 = - 8 + 2 / 2 = - 6 / 2 = - 3
Ответ: - 5 ; - 3.
№33.
x^2 + 17x + 16 = 0
a = 1
b = 17
c = 16
D = 17^2 - 4 × 1 × 16 = 289 - 64 = 225
x1 = - 17 - √225 / 2 = - 17 - 15 / 2 = - 32 / 2 = - 16
x2 = - 17 + 15 / 2 = - 2 / 2 = - 1
Ответ: - 16 ; - 1
№34.
x^2 + 10x + 16 = 0
a = 1
b = 10
c = 16
D = 100 - 64 = 36
x1 = - 10 - 6 / 2 = - 16 / 2 = - 8
x2 = - 10 + 6 / 2 = - 4 / 2 = - 2
Ответ: - 8 ; - 2.
№35.
x^2+ 19x + 18 = 0
a = 1
b = 19
c = 18
D = 361 - 72 = 289
x1 = - 19 - 17 / 2 = - 36 / 2 = - 18
x2 = - 19 + 17 / 2 = - 2 / 2 = -1
Ответ: - 18 ; - 1.
№36.
x^2 + 11x + 18 = 0
a = 1
b = 11
c = 18
D = 11^2 - 4 × 18 = 121 - 72 = 49
x1 = - 11 - 7 / 2 = - 18 / 2 = - 9
x2 = - 4 / 2 = - 2
Ответ: - 9 ; - 2.
№37.
x^2 + 9x + 18 = 0
a = 1
b = 9
c = 18
D = 81 - 72 = 9
x1 = - 9 - 3 / 2 = - 12 / 2 = - 6
x2 = - 6 / 2 = - 3
Ответ: - 6 ; - 3.
№38.
x^2 + 21x + 20 = 0
a = 1
b = 21
c = 20
D = 441 - 80 = 361
x1 = - 21 - 19 / 2 = - 40 / 2 = - 20
x2 = - 21 + 19 / 2 = - 1
Ответ: - 20 ; - 1.
№39.
x^2 + 12x + 20 = 0
a = 1
b = 12
c = 20
D = 144 - 80 = 64
x1 = - 12 - 8 / 2 = - 20 / 2 = - 10
x2 = - 4 / 2 = - 2
Ответ: - 10 ; - 2.
№40.
x^2 + 9x + 20 = 0
a = 1
b = 9
c = 20
D = 81 - 80 = 1
x1 = - 9 - 1 / 2 = - 10 / 2 = - 5
x2 = - 8 / 2 = - 4
Ответ: - 5 ; - 4.