In the xy-plane, the line x+y=k, where k is a constant, is tangent to the graph of y=x^2+3x+1 what is the value of k?

Question

anonymous · Answer

How would one approach this problem

anonymous · Answer

The derivative of a function represents the tangent line of its curve. This is the key to this problem.

anonymous · Answer

How would someone apply that concept to the first equation given?

anonymous · Answer

Or rather how would one set up the problem?

anonymous · Answer

Well... The question said that the line y=k-x is the tangent of y=x^2+3x+1.. What do you think that means considering the concept I wrote above?

anonymous · Answer

Y prime of x^2+3x+1 is equal to y= k-x ...?

anonymous · Answer

Yep!

anonymous · Answer

Oh !!! I know what I need to do. Thank you so much!

anonymous · Answer

I am sure you do!!