Question

Sa se calculeze imaginea functiei f:R-R f (x) =x la puterea 2 +x+1

Answer 1

functiede grad 2, a=1>0, va avea un minim si va tinde la ∞cand xtinde la- ∞ si la ∞

-b/2a=-1/2
 f(-1/2) =minim=1/4-1/2+1=3/4
Im f(x) = [3/4;∞)

altfel; 
f(x) = x²+x+1/4+3/4=(x+1/2)²+3/4≥3/4
 f(x)∈[3/4;∞)