1. Substitute \( y = x^2 \), transforming the quartic polynomial into a quadratic polynomial:
x^4 + 5x^2 + 4 = y^2 + 5y + 4
2. Solve the quadratic equation \( y^2 + 5y + 4 = 0 \) using the quadratic formula:
y = \frac{-5 \pm \sqrt{9}}{2}
y = \frac{-5 \pm 3}{2}
This gives us:
y_1 = -1
y_2 = -4
3. Substitute back \( y = x^2 \):
For \( y_1 = -1 \):
x^2 = -1
Roots:
x = \pm i
For \( y_2 = -4 \):
x^2 = -4
Roots:
x = \pm 2i
4. Combine all roots in factored form:
f(x) = (x - i)(x + i)(x - 2i)(x + 2i)
The factored form of the polynomial is:
f(x) = (x - i)(x + i)(x - 2i)(x + 2i)