Quartic Equation Calculator

Enter Coefficients for ax4 + bx3 + cx2 + dx + e = 0
a (coefficient of x4):
b (coefficient of x3):
c (coefficient of x2):
d (coefficient of x):
e (constant term):
Decimal Places:
Quartic Equation Diagram
-10 10 10 -10

Understanding Quartic Equations

What is a Quartic Equation?

A quartic equation is a polynomial equation of degree four. It's the most complex equation that can be solved by radicals according to the Abel-Ruffini theorem.

Formula

The general form of a quartic equation is:

\[ ax^4 + bx^3 + cx^2 + dx + e = 0 \]

Where:

  • \( a, b, c, d, \) and \( e \) are constants
  • \( a \neq 0 \)
  • \( x \) is the variable

Example Calculation

Let's solve this quartic equation:

\[ x^4 - 10x^3 + 35x^2 - 50x + 24 = 0 \]

Step 1: Identify coefficients
\( a = 1 \) \( b = -10 \) \( c = 35 \) \( d = -50 \) \( e = 24 \)
Step 2: Using Ferrari's method

First, we depress the quartic by substituting \( x = y - \frac{b}{4a} \):

\[ y = x + \frac{10}{4} = x + \frac{5}{2} \]

This gives us the depressed quartic:

\[ y^4 + py^2 + qy + r = 0 \]

Where:

\[ p = -\frac{3b^2}{8a^2} + \frac{c}{a} = -\frac{3(100)}{8} + 35 = -37.5 + 35 = -2.5 \]

\[ q = \frac{b^3}{8a^3} - \frac{bc}{2a^2} + \frac{d}{a} = \frac{-1000}{8} - 175 - 50 = -350 \]

\[ r = -\frac{3b^4}{256a^4} + \frac{b^2c}{16a^3} - \frac{bd}{4a^2} + \frac{e}{a} = -\frac{30000}{256} + \frac{3500}{16} - \frac{500}{4} + 24 = 15.625 \]

Final Solution

The roots are:

  • \( x_1 = 4 \)
  • \( x_2 = 3 \)
  • \( x_3 = 2 \)
  • \( x_4 = 1 \)

Verification

For x = 4:

\[ (4)^4 - 10(4)^3 + 35(4)^2 - 50(4) + 24 = 256 - 640 + 560 - 200 + 24 = 0 \]

For x = 3:

\[ (3)^4 - 10(3)^3 + 35(3)^2 - 50(3) + 24 = 81 - 270 + 315 - 150 + 24 = 0 \]

For x = 2:

\[ (2)^4 - 10(2)^3 + 35(2)^2 - 50(2) + 24 = 16 - 80 + 140 - 100 + 24 = 0 \]

For x = 1:

\[ (1)^4 - 10(1)^3 + 35(1)^2 - 50(1) + 24 = 1 - 10 + 35 - 50 + 24 = 0 \]

Visual Representation

X Y -10 -5 5 10 10 5 -5 -10 Root x₄=1 Root x₃=2 Root x₂=3 Root x₁=4 x₄=1 x₃=2 x₂=3 x₁=4 f(x) = x⁴ - 10x³ + 35x² - 50x + 24 Step 1: Find critical points where f'(x) = 0 Step 2: Verify f(1) = f(2) = f(3) = f(4) = 0 Step 3: Confirm these are the only roots