643, 644, 646
ա) x2 — 7x + 12 = 0
D = b2 — 4ac
D = 49 — 48 = 1
1 > 0
X1 + X2 = 7
X1 * X2 = 12 (++)
X1 = -b + √D / 2a
X2 = -b — √D / 2a
X1 = 7 + 1 / 2 = 4
X2 = 7 — 1 / 2 = 3
բ) x2 + 7x + 12 = 0
D = b2 — 4ac
D = 49 — 48 = 1
1 > 0
X1 + X2 = 7
X1 * X2 = 12 (- -)
X1 = -b + √D / 2a
X2 = -b — √D / 2a
X1 = -7 + 1 / 2 = -3
X2 = -7 — 1 / 2 = -4
գ) x2 + 5x — 14 = 0
D = b2 — 4ac
D = 25 + 56 = 81
81 > 0
X1 + X2 = 5
X1 * X2 = -14 (- +)
X1 = -b + √D / 2a
X2 = -b — √D / 2a
X1 = -5 + 9 / 2 = 2
X2 = -5 — 9 / 2 = -7
դ) x2 — 5x — 14 = 0
D = b2 — 4ac
D = 25 + 56 = 81
81 > 0
X1 + X2 = 5
X1 * X2 = -14 (- +)
X1 = -b + √D / 2a
X2 = -b — √D / 2a
X1 = 5 + 9 / 2 = 7
X2 = 5 — 9 / 2 = -2
ե) x2 + 1,27x — 1,46 = 0
D = b2 — 4ac
D = 1,6 + 5,84 = 7,44
7,44 > 0
X1 + X2 = -1,27
X1 * X2 = -1,46 (- +)
X1 = -b + √D / 2a
X2 = -b — √D / 2a
X1 = -1,27 + 7,44 / 2 = 3
X2 = -1,27 — 7,44 / 2 = -4,3
զ) x2 — 3/5x — 0,5 = 0
D = b2 — 4ac
D = 9,25 + 2 = 2,36
2,36 > 0
X1 + X2 = 3/5
X1 * X2 = -0,5 (- +)
X1 = -b + √D / 2a
X2 = -b — √D / 2a
X1 = 3/5 + 2,36 / 2 = 1,48
X2 = 3/5 — 2,36 / 2 = -0,88
է) x2 — 56x + 768 = 0
D = b2 — 4ac
D = 3136 — 3072 = 64
64 > 0
X1 + X2 = 56
X1 * X2 = 768 (+ +)
X1 = -b + √D / 2a
X2 = -b — √D / 2a
X1 = 56 + 8 / 2 = 32
X2 = 56 — 8 / 2 = 24
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