Polynomial Analysis
1. Problem: Analyze the polynomial $f(x) = (x + 1)(x - 1)(x - 3)$ of degree 3.
- Sum of coefficients: Expand and calculate the values.
- Even or Odd Degree: 3 (odd).
- End behavior: As $x \to \infty, f(x) \to \infty$; as $x \to -\infty, f(x) \to -\infty$ because leading term is $x^3$.
- Number of Turning Points: Maximum $2$ (degree - 1).
- X-intercepts: Solve $f(x) = 0$ at $x = -1, 1, 3$.
- Y-intercept: Evaluate $f(0) = (1)(-1)(-3) = 3$.
- Graph: S-shaped cubic curve crossing x-axis at roots.
2. For $f(x) = (x + 1)^2 (x - 3)^2$, degree 4:
- Sum coefficients found by expanding or plugging $x=1$.
- Degree even: $4$.
- Ends both up as leading $x^4$ positive.
- Turning points max $3$.
- X-intercepts: $-1$ (multiplicity 2), $3$ (multiplicity 2).
- Y-intercept: $f(0) = (1)^2(-3)^2=9$.
- Graph: W-shaped, touches x-axis at roots.
3. $f(x) = x + 6x^3 + 9x^2 - 4x - 12$ simplify to $6x^3+9x^2 -3x -12$.
- Degree 3, odd.
- Ends: left down, right up.
- Turning points max 2.
- X-intercepts: Solve $6x^3 + 9x^2 - 3x - 12=0$.
- Y-intercept: $f(0)=-12$.
4. $f(x) = (x+1)^2 (x-3)$ degree 3 odd.
- Sum coefficients expand or plug $x=1$.
- Ends as cubic odd degree.
- Turning points max 2.
- Roots at $-1$ (multiplicity 2), $3$.
- Y-intercept $f(0) = 1^2*(-3) = -3$.
5. $f(x) = (x-2)^2 - 5$ is quadratic transformed.
- Degree 2 even.
- Ends up (if positive leading coefficient).
- Turning points 1.
- Root solve $(x-2)^2=5$, $x=2 \pm \sqrt{5}$.
- Y-intercept $f(0) = 4 - 5 = -1$.
6. $f(x) = -x^2 - 3x - 4$, quadratic degree 2.
- Sum coefficients $-1 - 3 - 4 = -8$.
- Ends down (leading coefficient negative).
- Turning points 1.
- X-intercepts from quadratic formula.
- Y-intercept $f(0)=-4$.
7. $f(x) = 5x^2$, quadratic, degree 2.
- Sum coefficients 5.
- Ends up.
- Turning points 1.
- X-intercept at 0.
- Y-intercept 0.
8. $f(x) = x^3 + 2x^2 - 3x$, degree 3.
- Sum coefficients $1 + 2 - 3 = 0$.
- Ends cubic odd.
- Turning points 2.
- Roots at $x(x^2 + 2x -3)=0$, roots $0$, $-3$, and $1$.
- Y-intercept 0.
9. $f(x) = x^4 - 2x^2 + 1$, degree 4.
- Sum coef $1 - 2 + 1 =0$.
- Ends up.
- Turning points max 3.
- X-intercepts solve quartic.
- Y-intercept 1.
10. $f(x) = x^3 - 4x^2 + x + 6$, degree 3.
- Sum coef $1 - 4 + 1 + 6 = 4$.
- Ends odd cubic.
- Turning points 2.
- Roots via factor or approx.
- Y-int 6.
11. $f(x) = x^4 - 4x^3 - x^2 + 16x - 12$, degree 4.
- Sum coef $1 - 4 -1 + 16 -12 = 0$.
- Ends up.
- Turning points max 3.
- Roots via factorization.
- Y-intercept -12.
12. $f(x) = x^2 + 3$, degree 2.
- Sum coef $1 + 3 = 4$.
- Ends up.
- Turn 1.
- X-intercepts none (no real root).
- Y-int 3.
13. $f(x) = -x^4 + 3x^2 - x + 2$, degree 4.
- Sum coef $-1 + 3 -1 + 2 = 3$.
- Ends down.
- Turn max 3.
- Roots via approx.
- Y-int 2.
14. $f(x) = 2x^5 - 2x^3 + 10x^2 - 13x + 3$, degree 5.
- Sum coef $2 - 2 + 10 - 13 + 3 = 0$.
- Ends: left down, right up.
- Turn max 4.
- Roots complex.
- Y-int 3.
15. $f(x) = 2x(x - 5)(x - 2)$ degree 3.
- Sum coef expand: $2x(x^2 - 7x + 10) = 2x^3 -14x^2 + 20x$ coef sum $2 - 14 + 20 = 8$.
- Ends cubic odd.
- Turning points 2.
- X-int 0, 5, 2.
- Y-int 0.
Each graph shape corresponds to the degree and sign of leading term determining end behavior and number of turning points max degree-1. Intercepts found by roots and evaluating at zero.