Determine how a polynomial behaves as x → ±∞ using only the leading term — degree and leading coefficient tell the whole story
Only the leading term (highest-degree term) determines end behavior. All other terms become negligible as x grows large in magnitude.
| Degree | Lead coeff. | x → −∞ | x → +∞ |
|---|---|---|---|
| Even | Positive (a > 0) | y → +∞ ↑ | y → +∞ ↑ |
| Even | Negative (a < 0) | y → −∞ ↓ | y → −∞ ↓ |
| Odd | Positive (a > 0) | y → −∞ ↓ | y → +∞ ↑ |
| Odd | Negative (a < 0) | y → +∞ ↑ | y → −∞ ↓ |
Think of end behavior as the "highway" of the function — where does it go at the far left and far right of its domain?
No matter how many twists and turns a polynomial makes in the middle, the ends of its graph always follow a predictable pattern set by just two things: degree and leading coefficient sign.
Imagine driving on a highway that stretches infinitely in both directions. Your starting and ending destinations (up or down on the graph) are determined only by those two facts about the leading term — everything else is just scenery along the way.
One-on-one Algebra 2 tutoring makes end behavior, zeros, and graphing click — from reading the leading term to sketching the full curve confidently.