Find the equation of the line tangent to y^2=-16x and parallel to x+y=1.
Please help me with this or just give me an idea on how to answer this problem... Thanks!
If the line is parallel to , then its gradient is . (Why?)
You want the equation of the tangent that has the same gradient.
So
.
So when the gradient is ...
.
When we have
.
So we have the gradient and a coordinate that lies on the tangent.
Put this information into , solve for the unknown , and then you will have the equation of the tangent.