If f(x)=x2+4x+7, find:
(a): the smallest possible value of f(x).
(b): the value of x for which the smallest value occurs.
(c): the greatest possible value of 1/(x2+4x+7)

Question

If f(x)=x2+4x+7, find:
(a): the smallest possible value of f(x).
(b): the value of x for which the smallest value occurs.
(c): the greatest possible value of 1/(x2+4x+7)

anonymous · Answer

do u know derivatives?

anonymous · Answer

no

anonymous · Answer

do u know how to complete the square?

anonymous · Answer

yes

anonymous · Answer

then take this function and try completing its square...tell me

anonymous · Answer

When I was trying to complete the square I got stuck at: sqaure root(x+3)2=square root -1

phi · Answer

can you show your work?

phi · Answer

complete the square of
x^2+4x+7

phi · Answer

this explains how to do it http://www.khanacademy.org/math/algebra/quadtratics/v/completing-the-square

anonymous · Answer

see the equation can be written in the form of  (x+2)^2 +3. minimum value of square is 0. So minimum value of equation is 3.