Question

Determinati numerele realy x si y care au suma egala cu 2 si produsul egal cu -15.

Answer 1

x+y=2=>x=2-y
xy=-15=>(2-y)y=-15
2y-y²=-15
-y²+2y+15=0,sau
y²-2y-15=0
Δ=b²-4ac
Δ=4+60
Δ=64
√Δ=8
x₁=(2-8)/2=(-3)
x₂=(2+8)/2=5