| a | c | ||
< | |||
| b | d |
| a | a+c | c | |||
< | < | ? | |||
| b | b+d | d |
| a | c | ||
< | /*d (bo d > 0) | ||
| b | d |
| ad | |
< c /+a | |
| b |
| ad | ||
a + | < c + a | |
| b |
| ab + ad | |
< a + c | |
| b |
| a(b+d) | |
< a + c / : (b+d) (moge bo b+d jest na pewno > 0) | |
| b |
| a | a+c | ||
< | |||
| b | b+d |
| a | c | ||
< | /*b | ||
| b | d |
| bc | ||
a < | / +c | |
| d |
| bc | ||
a + c < | + c | |
| d |
| bc + cd | ||
a + c < | ||
| d |
| c(b+d) | ||
a + c < | /:(b+d) | |
| d |
| a+c | c | ||
< | |||
| b+d | d |