Consider a parabola y=x^(2)-4x+8
(a)Write down two straight lines that touch the parabola at only one point.
(b) Find the corresponding point of contact in (a).

Question

Consider a parabola y=x^(2)-4x+8
(a)Write down two straight lines that touch the parabola at only one point.
(b) Find the corresponding point of contact in (a).

anonymous · Answer

this a calculus class?

anonymous · Answer

nope

anonymous · Answer

ok then one could be the horizontal line that touches the vertex

anonymous · Answer

umm..

anonymous · Answer

i really don't know how you are going to find a line that touches the parabola at only one point, unless you know it is tangent to the parabola, which requires calculus
on the other hand any vertical line will only intersect the graph at one point, and so will the horizontal line through the vertex

anonymous · Answer

what does it means?

anonymous · Answer

the word "touches" is a bit ambiguous. if it means "tangent at one point" then you need calc
if it means "intersects" only at one point, any vertical line will work

anonymous · Answer

what class is this?  and how are you supposed to know such a thing?  it is a no brainer with calc, without it i cannot imagine what you are supposed to do.

anonymous · Answer

......well, that's fine..

anonymous · Answer

the vertex of this parabola is $(2,4)$ so the horizontal line $y=4$ will touch only and one point, namely at the vertex

anonymous · Answer

the vertical line $x=2$ will also cross only at one point, namely $(2,4)$ so that would be my answer

anonymous · Answer

maybe i ask my teacher tomorrow...thank you so much