Х в квадрат.+2 х-24=0

хв квадрат+8 х-13=0

21 хквадрат-2 х-3=0

X² + 2x - 24 = 0

D = 2² - 4*1 * (-24) = 4 + 96 = 100 = 10²

D > 0

x₁ = (- 2 - 10) / (2*1) = - 12/2 = - 6

x₂ = (- 2 + 10) / (2*1) = 8/2 = 4

x² + 8x - 13 = 0

D = 8² - 4*1 * (-13) = 64 + 52 = 116 = (2√29) ²

D> 0

x₁ = (- 8 - 2√29) / (2*1) = - 4 - √29 = - (4 + √29)

x₂ = (- 8 + 2√29) / (2*1) = - 4 + √29 = √29 - 4

21x²-2x - 3 = 0

D = (-2) ² - 4*21 * (-3) = 4 + 252 = 256 = 16²

D>0

x₁ = (- (-2) - 16) / (2*21) = (2 - 16) / 42 = - 14/42 = - 1/3

x₂ = (- (-2) + 16) / (2 * 21) = (2 + 16) / 42 = 18/42 = 3/7