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Rezolvati ecuatii de gradul 2 de forma completa:
a) x²-5x+6=0
b)x²+11x+18=0
c)x²+5x-14=0
d)x²-4x-21=0
va roggg multtttttttt


Răspuns :

a) (x-3)(x-2)=0
x₁=2,  x₂=3

b) (x+9)(x+2)=0
x₁=-9,  x₂=-2

c) (x-2)(x+7)=0
x₁=-7, x₂=2

d) (x-7)(x+3)=0
x₁=-3,  x₂=7

O seara buna!

a)x²-5x+6=0
a=1
b=-5
c=6
Δ=b²-4ac⇒Δ=(-5)²-4×1×6⇒Δ=25-24⇒Δ=1⇒√Δ=√1⇒Δ=1
x1x2=-b+-√Δ/2a⇒
x1=5+1/2⇒6/2⇒x1=3
x2=5-1/2⇒4/2⇒x2=2

b)x²+11x+18=0
a=1
b=11
c=18
Δ=b²-4ac⇒121-72⇒Δ=49⇒√Δ=√49⇒Δ=7
x1x2=-b+-√Δ/2a⇒
x1=-11+7/2⇒-4/2⇒x1=-2
x2=-11-7/2⇒-18/2⇒x2=9

c)x²+5x-14=0
a=1
b=5
c=-14
Δ=b²-4ac⇒Δ=25+56⇒Δ=81⇒√Δ=√81⇒Δ=9
x1x2=-b+-√Δ/2a
x1=-5+9/2⇒4/2⇒x1=2
x2=-5-9/2⇒-14/2⇒x2=-7

d)x²-4x-21=0
a=1
b=-4
c=-21
Δ=b²-4ac⇒Δ=16+84⇒Δ=100⇒√Δ=√100⇒Δ=10
x1x2=-b+-√Δ/2a⇒
x1=4+10/2⇒14/2⇒x1=7
x2=4-10/2⇒-6/2⇒x2=-3
sucees