Question

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Answer 1

a) x² + 8x - 9 = 0

a = 1

b = 8

c = - 9

∆ = b² - 4 . a . c

∆ = 8² - 4 . 1 . (-9)

∆ = 64 + 36

∆ = 100

x = - b ± √∆

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2a

x' = - 8 - 10

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2 . 1

x' = - 18

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2

x' = - 9

x" = - 8 + 10

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2 . 1

x" = 2

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2

x" = 1

S = (-9 , 1)

b) xv = - b

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2a

xv = - 8

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2 . 1

xv = - 8

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2

xv = - 4

yv = - ∆

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4a

yv = - 100

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4 . 1

yv = - 100

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4

yv = - 25

(-4 , -25)