Вправи: 413

413. Знайдіть xy, якщо:

1) x-1+y-1 x-1- y-1 = 2; 1x+ 1y1x- 1y = 2; y+xxyy-xxy = 2; y+x•xyxy(y-x) = 2; y+xy-x = 2.

2(y – x) = y + x;

2y – 2x = y + x;

–2x – x = y – 2y;

–3x = –y|: (–3y);

xy = 13;

2) 2x-1- y-1x-1+ 2y-1 = 5; 2x- 1y1x+ 2y = 5; 2y-xxyy+2xxy = 5; 2y-x•xyxy •(y+2x) = 5; 2y-xy+2x = 5.

5(y + 2x) = 2y – x;

5y + 10x = 2y – x;

10x + x = 2y – 5y;

11x = –3y| : 11y;

xy = –311.