Question

Sa se rezolve √ x+2= 4-x

Answer 1

$\sqrt{x+2}=4-x \\ \\ ( \sqrt{x+2})^{2} =(4-x )^{2} \\ \\ x+2=16-8x+ x^{2} \\ \\ x^{2} -8x-x+16-2=0 \\ \\ x^{2} -9x+14=0$

x²-9x+14=0  este ecuatie de gradul II de forma ax²+bx+c=0
Δ=b²- 4ac  =9²-4×14
Δ = 81-56⇒Δ=25
x₁=(-b+√Δ)/2a=(9+5)/2=7
x₂=(-b-√Δ)/2a=(9-5)/2=2

solutii:
x₁ = 7  si    x₂ = 2