Question

x+2y=7
radical din x^2-4y=8

Answer 1

x = 7 - 2y

Radical din (7-2y)^2 - 4y = 8

Ridici ambele la patrat => 49 - 28y + 4y^2 -4y = 64

Rezolvi exyatia de gradul 2

Answer 2

Explicație pas cu pas:

x+2y=7

√(x²-4y)=8

DVA: x²-4y≥0⇒x,y∈R

x+2y=7 |*2

x²-4y=64

2x+4y=14

x²-4y=14 (+)

x²+2x-14=0

Δ=4+4*14=60⇒√60=2√15

x1=(-2+2√15)/2=√15-1

x2=(-2-2√15)/2=-1-√15

y=(7-x)/2⇒y1=(8-√15)/2 si y2=(8+√15)/2

Bafta!