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Dan987654321
a fost răspuns

1) x la 2 -4x+5=0
2)x la 2+4x+13=0

Răspuns :

2-4x+5=0
4x+5=0+2
4x+5=2
4x=2-5
4x=-3
x=-3:4
X=-0,75

2+4X+13=0
4x+13=0-2
4x+13=-2
4x=-2:13
4x=-0,15
x=-0,15:4
X=0,038
Crisanemanuel
1)x²-4x+5=0 (a=1;b=-4;c=5)
Δ=b²-4ac=(-4)²-4·1·5=16-20=-4=i²·4(i²=-1→nr.complex)⇒√Δ=2i
x₁=(-b+√Δ)/2a=(4+2i)/2=2+i
x₂=(-b-√Δ)/2a=(4-2i)/2=2-i
2)x²+4x+13=0 (a=1;b=4;c=13)
Δ=b²-4ac=4²-4·1·13=16-52=-36=i²·36⇒√Δ=6i
x₁=(-b+√Δ)/2a=(-4+6i)/2=-4+3i
x₂=(-b-√Δ)/2a=(-4-6i)/2=-2-3i

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