1) a² - b² - a + b = ( a² - b²) - ( a -b) = ( a - b)( a + b) - ( a - b) = ( a -b)(a + b - 1)
3) xs - ys - x² + 2xy - y² = (xs - ys) - ( x² - 2xy + y²) = s( x - y) - ( x - y)² =
= s( x - y) - ( x - y)(x - y)= ( x - y)( s - x + y)
2) проверьте условие
A-3/2=1 1/2 a=1 1/2+3/2 a=3
3/2b=2 1/2 b=2 1/2:3/2 b=5/3=1 2/3 ⇒⇒a>b