What is the vertex of the function f(x)=2x^2+4x-16?

Question

anonymous · Answer

(-2,4) ?

jhannybean · Answer

standard form 

y = a(x-h)^2+k

y= 2x^2 + 4x - 16                      move the 16 to the other side

y + 16 = 2x^2 + 4x                     factor out a 2 from the right side.

y + 16 = 2(x^2 + 2x)                    complete the square

y + 16 + 2( 1 ) = 2( x^2 +2x + 1)       simplify.

y + 18 = 2(x + 1)^2

y = 2(x + 1)^2 - 18                      put it back in standard form.

y = 2( x - (-1))^2 + (-18)

anonymous · Answer

Refer to the attached Mathematica calculation.

jhannybean · Answer

Am i wrong? :\

jhannybean · Answer

Oh i see.

jhannybean · Answer

WELL!! we got the same thing, lol. (-1,-18) for the vertex. Thanks @robtobey :)