Вправи: 197

197. Виконайте дії:

1) 10x+y5x – 3y2x2 • x15y = 10x+y5x – 3y2 • xx2 • 15y = 10x+y5x – y5x = 10x+y-y5x = 10x5x = 2;

2) a2- 49- b2 : a-23+b – 23-b = a-2a+2(3+b)3-b3+b(a-2) – 23-b = a+23-b – 23-b = a+2-23-b = a 3-b;

3) x+y3x-y + 1x+y • x2- y23x-y = x+y3x-y + 1 • x-y(x+y)x+y(3x-y) = x+y3x-y + x-y3x-y = x+y+x-y3x-y = 2x3x-y;

4) m + m2+ mnn-m • mm+n = m + mm+nmn-m(m+n) = m + m2n-m = mn- m2+ m2n-m = mnn-m.