The quartic equation behind the graph is y = - 2 · x⁴ + 4 · x³ + 6 · x² - 8 · x - 8.
How to derive the expression for a quartic function
Quartic functions are fourth grade polynomials and according to the fundamental theorem of algebra, such kind of expressions have at least two real roots and at most four real roots. The graph of the picture shows a polynomial with two roots of multiplicity 2: x₁ = - 1, x₂ = 2.
y = a · (x + 1)² · (x - 2)² (1)
Where a is the leading coefficient.
If we know that (x, y) = (0, 4), then the leading coefficient of the polynomial is:
4 = a · (0 + 1) · (0 - 2)
4 = - 2 · a
a = - 2
Then, the quartic equation is equal to:
y = - 2 · (x + 1)² · (x - 2)²
y = - 2 · (x² + 2 · x + 1) · (x² - 4 · x + 4)
y = - 2 · [(x² + 2 · x + 1) · x² + (x² + 2 · x + 1) · (- 4 · x) + (x² + 2 · x + 1) · 4]
y = - 2 · (x⁴ + 2 · x³ + x² - 4 · x³ - 8 · x² - 4 · x + 4 · x² + 8 · x + 4)
y = - 2 · (x⁴ - 2 · x³ - 3 · x² + 4 · x + 4)
y = - 2 · x⁴ + 4 · x³ + 6 · x² - 8 · x - 8
To learn more on quartic equations: https://brainly.com/question/25285042
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