Вправи: 52

52. Скоротіть дріб:

1) (x+2)2- (x-2)248x = x2+ 4x+4-(x2- 4x+4)48x = x2+ 4x+4- x2+ 4x-448x = 8x48x = 16;

2) x3- y3x4- y4 = x-y(x2+ xy+ y2)x2- y2(x2+ y2) = x-y(x2+ xy+ y2)x-yx+y(x2+ y2) = x2+ xy+ y2x+y(x2+ y2);

3) (3b-9c)25b-15c = (3(b-3c))25(b-3c) = 9(b-3c)25(b-3c) = 9(b-3c)5.