-x²+16=0 1/2x²-14x=0 5x²-25x+30=0 3x²-4x+7=0
Ad. 1 )
-x²+16=0 D r-nia: x∈R
-(x²-16)=0 / :(-1)
x²-16=0
(x-4)·(x+4)=0
x-4=0 lub x+4=0
x=4 x= -4
Ad. 2)
1/2x²-14x=0 D r-nia: x∈R
½x²-14x=0 / ·2
x² - 28x = 0
x · (x - 28) = 0
x=0 lub x-28=0
x=28
Ad.3)
5x²-25x+30=0 D r-nia: x∈R
5x²-25x+30=0 / :5
x²- 5x + 6 = 0
a=1 b=-5 c=6
Δ=b²-4ac = (-5)² - 4 · 1 · 6 = 25-24 = 1
√Δ = 1
x₁= (-b-√Δ)/2a = [-(-5)-1] / 2·1 = 4/2 = 2
x₂= (-b+√Δ)/2a = [-(-5)+1] / 2·1 = 6/2 = 3
Ad.4)
3x²-4x+7=0 D r-nia: x∈R
3x²-4x+7=0
a=3 b=-4 c=7
Δ=b²-4ac = (-3)² - 4 · 3 · 7 = 9-84 = -75
Δ < 0 wówczas r-nie nie ma rozwiązań
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Ad. 1 )
-x²+16=0 D r-nia: x∈R
-(x²-16)=0 / :(-1)
x²-16=0
(x-4)·(x+4)=0
x-4=0 lub x+4=0
x=4 x= -4
Ad. 2)
1/2x²-14x=0 D r-nia: x∈R
½x²-14x=0 / ·2
x² - 28x = 0
x · (x - 28) = 0
x=0 lub x-28=0
x=28
Ad.3)
5x²-25x+30=0 D r-nia: x∈R
5x²-25x+30=0 / :5
x²- 5x + 6 = 0
a=1 b=-5 c=6
Δ=b²-4ac = (-5)² - 4 · 1 · 6 = 25-24 = 1
√Δ = 1
x₁= (-b-√Δ)/2a = [-(-5)-1] / 2·1 = 4/2 = 2
x₂= (-b+√Δ)/2a = [-(-5)+1] / 2·1 = 6/2 = 3
Ad.4)
3x²-4x+7=0 D r-nia: x∈R
3x²-4x+7=0
a=3 b=-4 c=7
Δ=b²-4ac = (-3)² - 4 · 3 · 7 = 9-84 = -75
Δ < 0 wówczas r-nie nie ma rozwiązań