We express both terms as perfect squares: x4 becomes (x2)2 and (x−z)4 becomes ((x−z)2)2. This allows us to apply the algebraic identity a2−b2=(a−b)(a+b) with a=x2 and b=(x−z)2.
Step 2: Apply identity a2−b2
Applying the difference of squares identity a2−b2=(a−b)(a+b), the expression factors into the product of [x2−(x−z)2] and [x2+(x−z)2].
Step 3: Factor the first factor using difference of squares
The first factor x2−(x−z)2 is also a difference of two squares. Using the same identity again with a=x and b=x−z, we get [x−(x−z)][x+(x−z)]=(x−x+z)(x+x−z)=z(2x−z).
Step 4: Expand and simplify the second factor
Now we expand the second factor using (x−z)2=x2−2xz+z2. Adding x2 gives x2+x2−2xz+z2=2x2−2xz+z2.
Step 5: Combine all factors
Combining the results of both factors, the complete factorisation of x4−(x−z)4 is z(2x−z)(2x2−2xz+z2).