2x-3y=7 17x=17 x=1
15x+3y=10 2x-3y=7 y=1,66
A^2-49=<span>(a+7)^2
</span>a^2-49a=<span>a(a-49)
</span>(a+7)(a-7)=<span>a^2+14a+49</span>
George Washington was the first American president.
Определите знак выражений:
а) sin 20 б) cos 70 в) tg 120
<span>г) ctg 240 д) sin( -45) е) tg( -130)</span>
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