Кароч,угол Б в треугольнике равен 180-68=112¤,а так как сумма углов треугольника =180¤=>угол А=180-(28+112)=40¤
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А)2х-3у-11х+8у=5у-9х
б)5(2а+1)-3=10а+5-3=10а+2
в)(14х-х-1)+(2х+6)=13х-1+2х+6=15х+5
Под корнем должно стоять положительное значение или ноль.
1) m²+1>0 всегда
2) (√100m)² вот это выражение,при m<0 100m<0 и под корнем получаем отрицательное значение,чего быть не должно
3) 4 ImI≥0 так как ImI≥0
4) 2m²≥0 всегда
Ответ:2).
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