1)
(4x+1)(x-3)=12.
4х²+ х - 12х - 3 = 12
4х² - 11х - 15 = 0
D = b² - 4ac
D = 11² - 4 * 4 * (-15)=121+ 240 = 361
√D = √361 = 19
x₁ = (11+19)/(2*4) = 30/8=3,75
x₂ = (11-19)/(2*4) = -8/8= - 1
Ответ: - 1; 3,75
2)
(x+2)(x-3)-(2x-5)(x+3)=x(x-5)
x²- 3x + 2x - 6 - 2x² + 5x - 6x + 15 = x² - 5x
- 2x² + 3x + 9 = 0
D = b² - 4ac
D = 3² - 4 * (-2) * 9 = 9 + 72 = 81
√D = √81 = 9
x₁ = (-3+9)/(-2*2) = 6/(-4)= -1,5
x₂ =(-3-9)/(-2*2) = -12/(-4)= 3
Ответ: -1,5; 3.