tentukan perkalian -5a²bx4ab

-5a^2b × 4ab =
(-5×4)(a^2×a)(b×b) =
(-20)(a^3)(b^2) =
-20a^3b^2

-5a²b x 4ab = ((-5)x(4)).(a²)(a).(b)(b)
                   = -20 . a³ . b²
                   = -20a³b²