Вправи: 663

663. Звільніться від ірраціональності в знаменнику дробу:

1) 11- 2 = 1 •(1+ 2)1- 2(1+ 2) = 1+ 21-2 = 1+ 2-1 = –1 – 2;

2) 72+ 3 = 7 •(2- 3)2+ 3(2- 3) = 7 •(2- 3)2-9 = 7 •(2- 3)-7 = 2- 3-1 = –2 + 3 = 3 – 2;

3) 47- 5 = 4 •(7+ 5)7- 5(7+ 5) = 4 •(7+ 5)7-5 = 4(7+ 5)2 = 2(7+ 5);

4) 710+ 3 = 7(10- 3)10+ 3(10- 3) = 7(10- 3)10-3 = 7(10- 3)7 = 10- 3;

5) 211- 2 = 2 •(11+ 2)11- 2(11+ 2) = 2(11+ 2)11-2 = 2(11+ 2)9;

6) 35+ 2 = 3(5- 2)5+ 2(5- 2) = 3(5- 2)5-2 = 3(5- 2)3 = 5 – 2;

7) 1x- 2 = 1 •(x+ 2)x- 2(x+ 2) = x+ 2x-2;

8) 1y+ x = 1 •(y- x)y+ x(y- x) = y- xy-x.