English
If p and q are polynomials over a ring with no zero divisors, then (p q).scaleRoots r = p.scaleRoots r · q.scaleRoots r.
Русский
Если p и q — многочлены над кольцом без делителей нуля, то (p q).scaleRoots r = p.scaleRoots r · q.scaleRoots r.
LaTeX
$$$\text{mul_scaleRoots'}(p, q, r) : (p q).\scaleRoots r = p.\scaleRoots r \cdot q.\scaleRoots r$$$
Lean4
theorem mul_scaleRoots' (p q : R[X]) (r : R) (h : leadingCoeff p * leadingCoeff q ≠ 0) :
(p * q).scaleRoots r = p.scaleRoots r * q.scaleRoots r := by
rw [← mul_scaleRoots, natDegree_mul' h, tsub_self, pow_zero, one_smul]