.....................................................
4.3х+1-1+2х/5Больше =х
5х/5 больше =х
х=х
Расскрывай скобки
20х+5у-3у-6х
14х+2у
Tga - ctga = 4
(tga - ctga)² = 4²
tg²a - 2tga*ctga + ctg²a = 16 tga * ctga = 1
tg²a - 2 * 1 + ctg²a = 16
tg²a - 2 + ctg²a = 16
tg²a + ctg²a = 16 + 2
tg²a + ctg²a = 18