Question

Subiectul 3 ex 1 c); 2 a),b)
Subiectul 2 ex 2, 4

Answer 1

II/2
x^4+x²+1=x^4+2x²-x²+1=(x^4+2x²+1)-x²=(x²+1)²-x²=(x²-x+1)(x²+x+1)
II/3
9x²-24x+16=(3x)²-2·(3x)·4+4²=(3x+4)²
III/1/c
x²-4x-12=x²-6x+2x-12=x·(x-6) +2·(x-6)=(x-6)(x+2)
II/2/a
√(n²-2n+1+16)=√[(n-1)²+16]
ca sa fie natural trebuie sa fie patrat perfect si (n-1)²trebuie sa fie :
(n-1)²=0 ,n=1
(n-1)²=9⇒
n-1=-3 ⇒n=-2
n-1=3 ⇒n=4
n={-2,1,4}
b)
x²+12x+31=x²+12x+36-5=(x+6)²-5
x+6=0, x=-6 ⇒min=-5