Question

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Answer 1

3) 6x² + x - 1 = 0

∆ = b² - 4 . a . c

∆ = 1² - 4 . 6 . (-1)

∆ = 1 + 24

∆ = 25

x = - b ± ✓∆

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2a

x' = - 1 - 5

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2 . 6

x' = - 6 (÷6)

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12 (÷6)

x' = - 1

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2

x" = - 1 + 5

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2 . 6

x" = 4 (÷4)

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12 (÷4)

x" = 1

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3

S = {-1/2 , 1/3}

4) 3x² - 7x + 2 = 0

∆ = b² - 4 . a . c

∆ = (-7)² - 4 . 3 . 2

∆ = 49 - 24

∆ = 25

x = - b ± √∆

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2a

x' = -(-7) - 5

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2 . 3

x' = 7 - 5

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6

x' = 2 (÷2)

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6 (÷2)

x' = 1

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3

x" = -(-7) + 5

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2 . 3

x" = 7 + 5

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6

x" = 12

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6

x" = 2

S = {1/3 , 2}

5) 2x² - 7x - 15 = 0

∆ = b² - 4 . a . c

∆ = (-7)² - 4 . 2 . (-15)

∆ = 49 + 120

∆ = 169

x = - b ± √∆

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2a

x' = -(-7) - 13

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2 . 2

x' = 7 - 13

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4

x' = - 6 (÷2)

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4 (÷2)

x' = - 3

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2

x" = -(-7) + 13

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2 . 2

x" = 7 + 13

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4

x" = 20

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4

x" = 5

S = {-3/2 , 5}

6) 4x² - 12x + 9 = 0

∆ = b² - 4 . a . c

∆ = (-12)² - 4 . 4 . 9

∆ = 144 - 144

∆ = 0

x = - b ± √∆

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2a

x = -(-12) - 0

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2 . 4

x = 12 - 0

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8

x = 12 (÷4)

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8 (÷4)

x = 3

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2

S = {3/2}

7) 2x² - 8x + 8 = 0

∆ = b² - 4 . a . c

∆ = (-8)² - 4 . 2 . 8

∆ = 64 - 64

∆ = 0

x = - b ± √∆

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2a

x' = -(-8) - 0

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2 . 2

x' = 8 - 0

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4

x' = 8

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4

x' = 2

S = {2}