Հանրահաշիվ 2017-2018

571.

ա) 3x² + 4x + 5

a — 3, b — 4, c — 5

բ) 2x² — 5x — 7

a — 2, b — ( — 5 ), c — ( — 7 )

գ) — 5x² + 3x — 1

a — ( — 5 ), b — 3, c — ( — 1)

դ) 6x² + x — 2

a — 6, b — 1, c — ( — 1 )

ե) x² — x + 7

a — 1, b — ( — 1), c — 7

զ) — x² + x + 1

a — ( — 1 ), b — 1, c — 1

572.

ա) a = 3, b = 4, c = 5

3x² + 4x + 5

բ) a = 3, b = — 2, c = 6

3x² — 2x + 6

գ) a = 1, b = — 1, c = 2

x² — x + 2

դ) a = — 1, b = 3, c = — 2

— x² + 3x — 2

573.

ա) 2x² + 5x + 3

D = 25 – 4 x 2 x 3 = 25 – 24 = 1

բ) 2x² – 5x + 3

D = 25 – 4 x 2 x 3 = 25 – 24 = 1

գ) 2x² + 5x – 3

D = 25 – 4 x 2 x (-3) = 25 + 24 = 49

դ) 2x² – 5x – 3

D = 25 – 4 x 2 x (-3) = 24 + 24 = 49

ե) x² – 4x + 5

D = 16 – 4 x 1 x 5 = 16 – 20 = -4

զ) x² + 6x + 9

D = 36 – 4 x 1 x 9 = 36 – 36 = 0

է) x² + 2x + 1

D = 4 – 4 x 1 x 1 = 4 – 4 = 0

ը) -3x² + 5x – 2

D = 25 – 4 x (-3) x (-2) = 25 – 24 = 1

թ) x² + 2x + 2
D = 4 – 4 x 1 x 2 = 4 – 8 = -4

394.
ա) x-1>0   x>1 x є (1;+∞)

բ) x+5<0   x<-5 x є (-∞;-5)

գ) x-0,5<0   x<0,5 x є (-∞;0,5)

դ) 3+x>0   x>-3 x є (-3;+∞)

ե) 7+x>0   x>-7 x є (-7;+∞)
զ) x-1 1/3<0   x<1 1/3   x є (-∞;1 1/3)

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