158.
а) a² - a+b = a² - a+b = 2a² - (a+b)(a-b) = 2a² - a²+b² = a² +b²
(a-b)² 2a-2b (a-b)² 2(a-b) 2(a-b)² 2(a-b)² 2(a-b)²
б) y - x+y = y - x+y = y + x+y = y²+(x+y)(x-y) =
(x-y)² y²-xy (x-y)² -(xy-y²) (x-y)² y(x-y) y(x-y)²-x
=y² +x²-y² = x²
y(x-y)² y(x-y)²
в) x+y + x² = x+y + x² = -(x+y)(y-x) +3x² = -y² +x² +3x² =
3x-3y (y-x)² -3(y-x) (y-x)² 3(y-x)² 3(y-x)²
= 4x² -y²
3(y-x)²
г) a+b + a = a+b + a = -(a+b)(b-a) +a² = -b² +a² +a² = 2a² -b²
a² -ab (b-a)² -a(b-a) (b-a)² a(b-a)² a(b-a)² a(b-a)²