Which of the following equations is of a parabola with a vertex at (0, -5)?
a.y= (x- 5)^2
b.y= (x+ 5)^2
c.y=x^2- 5
d.y=x^2+ 5

Question

Which of the following equations is of a parabola with a vertex at (0, -5)?
a.y= (x- 5)^2
b.y= (x+ 5)^2
c.y=x^2- 5
d.y=x^2+ 5

anonymous · Answer

Hint: An equation of the form $y=(x-\color{red} a)^2+\color{blue} b$ has the vertex $(\color{red} a, \color{blue} b)$.

nenadmatematika · Answer

the answer is b...do the first derivative of y and you'll get 2(x+5), then set it to be zero (geometrically this means that you ask for the point where the slope of the tangent line is zero, and at parabola only possible point is vertex)....so you get x=-5 and when you plug it back in equation of parabola you get y=0 so the answer is (-5,0)

nenadmatematika · Answer

of course b is your answer :D

anonymous · Answer

mixed answers...one says c, one says a, and one says b

nenadmatematika · Answer

what can I do...I'm pretty sure about this :D I can draw your parabola..it looks like this|dw:1339788022571:dw|