Х^2-7 х + 12 = 0, 5 х^2-3x-2=0, 3x^2+7x+4=0, 2x^2+x+3=0, 4x^2-12x+9=0

Question

София Казакова

Математика

6 августа, 15:24

Х^2-7 х + 12 = 0, 5 х^2-3x-2=0, 3x^2+7x+4=0, 2x^2+x+3=0, 4x^2-12x+9=0

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Кристина Логинова · Answer 1

1) х^2 - 7 х + 12 = 0.

D = b^2 - 4ac = (-7) ^2 - 4 * 1 * 12 = 49 - 48 = 1.

x1 = (-b + √D) / 2a = (7 + 1) / 2 = 8/2 = 4.

x2 = (-b - √D) / 2a = (7 - 1) / 2 = 6/2 = 3.

2) 5x^2 - 3x - 2 = 0.

D = (-3) ^2 - 4 * 5 * (-2) = 9 + 40 = 49.

x1 = (3 + 7) / (2 * 5) = 10/10 = 1.

x2 = (3 - 7) / (2 * 5) = - 4/10 = - 2/5.

3) 3x^2 + 7x + 4 = 0.

D = 7^2 - 4 * 3 * 4 = 49 - 48 = 1.

x1 = (-7 + 1) / (2 * 3) = - 6/6 = - 1.

x2 = (-7 - 1) / 6 = - 8/6 = - 1 1/3.

4) 4x^2 - 12x + 9 = 0.

D = (-12) ^2 - 4 * 4 * 9 = 144 - 144 = 0.

x = - b/2a = 12 / (2 * 4) = 12/8 = 1 4/8 = 1 1/2.