Вправи: 414

414. Знайдіть mn, якщо:

1) n-1+ m-1n-1- m-1 = 3; 1n+ 1m1n- 1m = 3;m+nmnm-nmn = 3; m+n•mnmn •(m-n) = 3; m+nm-n = 3;

3(m – n) = m + n;

3m – 3n = m + n;

3m – m = n + 3n;

2m = 4n |: 2n;

mn = 2.

2) m-1- 4n-13n-1+ m-1 = 5; 1m- 4n3n+ 1m = 5; n-4mmn3m+nmn = 5;

n-4m•mnmn(3m+n) = 5; n-4m3m+n = 5.

5(3m + n) = n – 4m;

15m + 5n = n – 4m;

15m + 4m = n – 5n;

19m = –4n |: 19n;

mn = –419.