1.2х^2+7х+3=0 2.2х^2-х-1=0 3.8х^2+7-1=0 4.4х^2+16х+15=0 5.5х^2+42х+16=0 6.9х^2+15х-60=0

Решим дискриминанты:

1. 2x²+7x+3 = 0

D = b²-4ac => 7²-4*2*3 = 49-24 = √25 = 5 > 0, 2 корня.

x = $\frac{-b+-\sqrt{D} }{2a}$

x₁ = $\frac{-7+5}{4} = \frac{-2}{4} = -0,5$

x₂ = $\frac{-7-5}{4} = -3$

Ответ: -3 ; -0,5.

2. 2x²-x-1 = 0

D = (-1²)-4*2*(-1) = √9 = 3 > 0, 2 корня.

x₁ = $\frac{1+3}{4} = 1$

x₂ = $\frac{1-3}{4} = \frac{-2}{4} = -0,5$

Ответ: -0,5 ; 1.

3. 8x²+7-1 = 0

D = 7²-4*8*(-1) = 49+32 = √81 = 9 > 0, 2 корня.

x₁ = $\frac{-7+9}{16} = \frac{2}{16} = 0,125$

x₂ = $\frac{-7-9}{16} = -1$

Ответ: -1 ; 0,125.

4. 4x²+16x+15 = 0

D = 16²-4*4*15 = 256-240 = √16 = 4 > 0, 2 корня.

x₁ = $\frac{-16+4}{8} = \frac{-12}{8} = -1,5$

x₂ = $\frac{-16-4}{8} = \frac{-20}{8} = -2,5$

Ответ: -2,5 ; -1,5.

5. 5x²+42x+16 = 0

D = 42²-4*5*16 = 1764-320 = √1444 = 38 > 0, 2 корня.

x₁ = $\frac{-42+38}{10} = \frac{-4}{10} = -0,4$

x₂ = $\frac{-42-38}{10} = \frac{-80}{10} = -8$

Ответ: -8 ; -0,4.

6. 9x²+15x-60 = 0

D = 15²-4*9*(-60) = 225+2160 = 2385 > 0, 2 корня.

x₁ = $\frac{-15+2385}{18} = 131,6$

x₂ = $\frac{-15-2385}{18} = \frac{-2400}{18} = -133,3$

Ответ: -133,3 ; 131,6.