(1.) The function f(x)=3x2−2x+5 is continuous for all x∈R as polynomial.
and the first derivative of this function f(x) is
f′(x)=6x−2f′(x)=0⟹6x−2=0⟹x=31If x>31,f′(x)>0,f(x) is strictly increasing.
f(1)=3(1)2−2(1)+5=6f(2)=3(2)2−2(2)+5=13f(3)=3(3)2−2(3)+5=26⟹f:[1,2]→[6,13]⟹f:[2,3]→[13,26]⟹f:{1,2,3}→{6,13,26}
Comments
Leave a comment