a² - 3a + b² + 3b - 2ab = (a² - 2ab + b²) - (3a - 3b) = (a - b)² - 3(a - b) =
= (a - b)(a - b - 3);
f(x)' = (x^2/2x-1)' = ( (x^2)' (2x-1) -x^2*(2x-1)' ) / (2x-1)^2 =
= ( 2x (2x-1) - x^2*2 ) / (2x-1)^2 = ( 4x^2 -2x - 2 x^2 ) / (2x-1)^2 =
= ( 2x^2 -2x ) / (2x-1)^2 = 2x( x -1 ) / (2x-1)^2
sina*cosa*cos2a=sina*cosa*(cos^2 a - sin^2 a)=sina*cos^3 a-sin^3 a * cosa=== незнаю извини