6x²+x-1=0 x²-5x-1=0

2x²-5x+3=0 x²+3x+1=0

3x²+7x-6=0

1). 6x² + x - 1 = 0

D = b² - 4ac

D = 1 - 4 * 6 * (- 1) = 1 + 24 = √25 = 5

x₁ = - 1 + 5 / 2*6 = 4/12 = 1/3

x₂ = - 1 - 5/2*6 = - 6/12 = - 1/2

2) x² - 5x - 1 = 0

D = 25 - 4 * 1 * (- 1) = 25 + 4 = 29

x₁ = 5 + √29/2

x² = 5 - √29/2

3) 2x² - 5x + 3 = 0

D = 25 - 4 * 2 * 3 = 25 - 24 = √1

x₁ = 5 + 1 / 4 = 6/4 = 3/2

x₂ = 5 - 1 / 4 = 1

4) x² + 3x + 1 = 0

D = 9 - 4 * 1 * 1 = 9 - 4 = √5

x₁ = - 3 + √5 / 2

x₂ = - 3 - √5/2

5) 3x² + 7x - 6 = 0

D = 49 - 4 * 3 * (- 6) = 49 + 72 = 121

x₁ = - 7 + 11 / 6 = 4/6 = 2/3

x₂ = - 7 - 11 / 6 = - 18/6 = - 3