If f(x) = 7x3 - kx2 + x - 7k, find a number k such that the graph of f contains the point (-1, 4).

This is a practice problem assigned by my precalculus teacher, but there is no explanation in the textbook as to how I should do it. Any help and/or explanations would be greatly appreciated.

Question

If f(x) = 7x3 - kx2 + x - 7k, find a number k such that the graph of f contains the point (-1, 4). 

This is a practice problem assigned by my precalculus teacher, but there is no explanation in the textbook as to how I should do it. Any help and/or explanations would be greatly appreciated.

anonymous · Answer

Change f(x) to y: y = 7x3 - kx2 + x - 7
Plug in for x and y.  Solve for k.

anonymous · Answer

Did that help?

anonymous · Answer

YES! You are AMAZING. Best response for sure! Thanks!!!

anonymous · Answer

No problem!

anonymous · Answer

By the way, where I typed 7x3 and kx2, the 3 and 2 were supposed to be exponents! I hope you took that into account!

anonymous · Answer

The equation should still solve itself even with the exponents.

anonymous · Answer

Yep, it did, gotcha!