# pre-cal: formula for line crossing 1/x at 0.4 and 2

#### sbrooks

##### New member
Need help to get started.....to set it up
the formula for the line intersecting the graph of f(x)=1/x
at 0.4 and x=2
is given by y=b=mx,
where b is .... and m is ....

#### stapel

##### Super Moderator
Staff member
sbrooks said:
the formula for the line....is given by y=b=mx....
As was explained to you in your other thread, the equation for a straight line, in slope-intercept form, is "y = mx + b". You cannot have two "equals" signs in this equation! :shock:

To find the points where the lines cross (where they are the same), plug the given x-values into the given formula, and solve for the corresponding y-values. Use the two points to find the slope of the line, using the "slope" formula you've memorized. Then pick either one of the points (it doesn't matter which), and, together with the slope you've found, plug into whichever line formula you're using to find the line's equation. :idea:

If you get stuck, please reply showing your work and reasoning. Thank you! Eliz.