Question #0519e

Question

1188 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-03-08T10:27:15

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

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'.