Ответ:
x = {1; 3}
Объяснение:
-x^2+4x=3
x^2 - 4x + 3 = 0
x^2 - 4x + 4 - 1 = 0
(x^2 - 4x + 4) - 1 = 0
(x - 2)^2 - 1^2 = 0
(x-2 -1) (x-2 +1) = 0
( x-3) (x-1) = 0
x-3 =0 ---> x = 3
x-1 =0 ----> x = 1