Question

Question #0519e

Answer 1

You need more information to assign a value to `k` so is the wording of this question complete and/or correct?

Explanation:

NOTE THAT you are allowed to call a straight line graph a curve.

Consider the standardised form of `y=mx+c`

Now consider the given curve `y=k/1-2x`

`k/1` is the same as just `k` giving:

`y=k-2x`

Put this in the same order as the standardised form and we have

`color(red)(y=-2x+k) larr" This is the equation of a strait line!"`

We are told that the tangent has the gradient of -2 which matches the -2 in `y=-2x+k`

So the tangent is parallel to the line. The very fact it is a tangent (to a straight line plot) means that it coincides with the line.

Thus any point (x,y) will be on both the original line and its tangent.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Set `x=2`

`y=-2x+k`

`y=-2(2)+k`

`y=-4+k`

So `" " k=y+4`

In other words you need to know a value for `y` to determine the value of `k`

A state where you can not get an answer is called 'indeterminate'.