factor x^4-4x^2
1) Let's factor in ℝ: x4 -4x2
For x4 -4x2, we recognize a difference of two squares: (x2)2 -(2x)2. Apply a2 -b2 = (a -b)·(a + b), with a = x2 and b = 2x
You can factorize the expression: x4 -4x2 into: (x2 -2x)·(x2 + 2x)
2) Let's factor in ℝ: (x2 -2x)·(x2 + 2x)
⇥2.1) Let's factor in ℝ: (x2 -2x)
⇥You can write the expression in factored form: x·(x -2)
▷The factor (x2 -2x) factors as: x·(x -2)
⇥2.2) Let's factor in ℝ: (x2 + 2x)
⇥This expression can be factorized into: x·(x + 2)
▷The factor (x2 + 2x) factors as: x·(x + 2)
3) Let's replace each factor by its factorization: x·(x -2)·x·(x + 2)
ⓘ Multiplying powers with the same base adds the exponents: x·x = x2
x2·(x -2)·(x + 2)
ⓘ Factor out the common factor x2
▶Factored expression:   x2·(x + 2)·(x -2)