Question

Rezolvati in multimea numerelor reale ecuatia (x+1)*(x-3)=4

Answer 1

(x+1)(x-3)=4
x^2-2x-3=4
x^2-2x-3-4=4-4
x^2-2x-7=0
A=1
B=-2
C=-7
Δ=b^2-4ac
Δ=4-(-28)
Δ=4+28
Δ=32
Δ>0
x=(2+/-√32)/2
2/2=1
√32/2=4√2/2=2√2
x1=1+2√2
x2=1-2√2
x∈R
x∈{(1+2√2);(1-2√2)}