Question

Ajutor si explicati ca nu am inteles.Astept doua raspunsuri pana la 16:00. Cele mai bune si dau coroana.

Answer 1

ecuatii de gradul al II lea: ax²+bx+c
Δ=b²-4ac
x₁=(-b+√Δ)/2a
x₂=(-b-√Δ)/2a

1)
x²+7x+12=0
Δ=b²-4ac=49-4×1×12=49-48=1
x₁=(-b+√Δ)/2a=(-7+1)/2=-3
x₂=(-b-√Δ)/2a=(-7-1)/2=-8/2=-4

2)
x²-3x+2=0
Δ=b²-4ac=9-4×2×1=9-8=1
x₁=(-b+√Δ)/2a=(3+1)/2=2
x₂=(-b-√Δ)/2a=(3-1)/2=1

3)
x²-x-12=0
Δ=b²-4ac=1+48
x₁=(-b+√Δ)/2a=(-1+7)/2=3
x₂=(-b-√Δ)/2a=(-1-7)/2=-4

4)
x²+9x+20=0
Δ=b²-4ac=81-80=1
x₁=(-b+√Δ)/2a=(-9+1)/2=-4
x₂=(-b-√Δ)/2a=(-9-1)/2=-10/2=-5

5)
x²-11x+30=0
Δ=b²-4ac=121-120=1
x₁=(-b+√Δ)/2a=(11+1)/2=6
x₂=(-b-√Δ)/2a=(11-1)/2=5