при а= - 2,5 ⇒ - 2,5 + 5 = 2,5
1)х/7=200-72
х/7=128
х=128*7
х=896
2)<span>а-293=207:9</span>
<span>а-293=23</span>
<span>а=293+23</span>
<span>а=316</span>
<span>3)<span>у• 6 =800-512</span></span>
<span><span>у*6=288</span></span>
<span><span>у=288/6</span></span>
<span><span>у=48</span></span>
Ответ:
-2x-8
Подробное решение:
(x-1)2-(x+3)(x-3)=x2-2x+1-x2-9=-2x-8