Question

1. Ecuatia $x^{2} + 3x + 4 = 0$ nu are solutii reale. A / F - cu explicatii!

2. Multimea solutiilor ecuatiei $x^{2} + 6x - 7 = 0$ este:
A. {-7; -1} ; B. {-1; 7} ; C. {-7; 1} ; D. {1; 7} . - cu explicatii!

P.S. Ofer coroana celui mai bun raspuns.

Answer 1

1. ax²+bx+c=0, Δ=b²-4ac, Δ<0 ecuatia nu are solutii reale, Δ≥0, ecuatia are solutii reale
x²+3x+4=0
a=1, b=3, c=4, Δ=9-4*1*4=9-16=-7<0, ecuatia  nu are solutii reale   A
2. x²+6x-7=0, x1,2=(-b+-√Δ)/2a
a=1, b=6, c=-7
Δ=36+28=64, √Δ=8
x1=(-6+8)/2=1
x2=(-6-8)/2=-7
S={-7, 1}      B