Вправи: 394

394. Спростіть вираз:

1) 1y2 – y^–2 = 1y2 – 1y2 = 0;

2) (a + 10)^–1 + 9a+10 = 1a+10 + 9a+10 = 10a+10;

3) a(a + 4)^–1 + 4(a + 4)^–1 = aa+4 + 4a+4 = a+4a+4 = 1;

4) 77+n + n(7 + n)^–1 = 77+n + n7+n = 7+n7+n = 1;

5) (m + n)^–1 – (m + n)⁰ = 1m+n – 1^\m+n = 1-m-nm+n;

6) (4 + x)^–1 – (4 – x)^–1 = 1\4-x4+x – 1\4+x4-x = 4-x-4-x4+x(4-x) = –2x16-x2 = 2xx2- 16.