(5a−2b)2−0,5a(50a−40b)+(3a−2b)(2b+3a) = 10а -4b -25a^2 +20ab +6ab +9a^2 -4b^2 -6ab = -16a^2 -4b^2 +20ab +10a -4b
(5a−2b)2−0,5a(50a−40b)+(3a−2b)(2b+3a) = 10а -4b -25a^2 +20ab +6ab +9a^2 -4b^2 -6ab = -16a^2 -4b^2 +20ab +10a -4b