Вправи: 165

165. Виконайте дії:

1) 4y-2\3515 + 3+3y\2125 + 1-3y\1535 = 140y-70+63+63y+15-45y525 = 158y+8525;

2) yxy-x2 + xxy-y2 = yx(y-x) + xy(x-y) = y\yx(y-x) – x\xy(y-x) = y2- x2xy(y-x) = y-x(y+x)xy(y-x) = y+xxy;

3) 1-tt2- t – t+11-t2 = 1-tt(t-1) – t+11-t(1+t) = –t-1t(t-1) + 1t-1 = –1\t-1t + 1\tt-1 = -t+1+tt(t-1) = 1t(t-1);

4) 4t2- 9 – 2t2+ 3t = 4\tt-3(t+3) – 2\t-3t(t+3) = 4t-2t+6tt-3(t+3)2 = 2t+6tt-3(t+3)2 = 2(t+3)tt-3(t+3)2 = 2tt-3(t+3) = 2t(t2- 9).