Question

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A)x la putera 2 - 6x - 31 = 0
B)4x la puterea 2 - 13x - 12 = 0
C) 5x la puterea 2 + 9x - 2 = 0

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Answer 1

Răspuns:

Explicație pas cu pas:

a) x²-6x-31 = 0

a = 1 ; b = -6 ; c = -31

Δ = b²-4ac = (-6)²-4·1·(-31) = 36+124 = 160

√Δ = √160 = 4√10

x₁,₂ = (-b±√Δ)/2a = (6±4√10)/2 = 3±2√10

x₁ = 3-2√10 ; x₂ = 3+2√10

b) 4x²-13x-12 = 0

a = 4 ; b = -13 ; c = -12

Δ = (-13)²-4·4·(-12) = 169+192 = 361

√Δ = √361 = 19

x₁,₂ = (-b±√Δ)/2a = (13±19)/8

x₁ = -6/8 => x₁ = -3/4

x₂ = 32/8 => x₂ = 4

c) 5x²+9x-2 = 0

a = 5 ; b = 9 ; c = -2

Δ = 9²-4·5·(-2) = 81+40 = 121

√Δ = √121 = 11

x₁,₂ = (-9±11)/10

x₁ = -20/10 => x₁ = -2

x₂ = 2/10 => x₂ = 1/5

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Answer 2

Răspuns:

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