7х-5=3х+7
7х-3х=7+5
4х=12
х=12:4
х=3
<span>(7a + 1)²</span><span> </span><span>- 28a</span>
<span>49a²+14a+1-28a</span>
<span>49a²-14a+1=0</span>
<span>a²-2/7a+1/49=0</span>
<span>a=1/7±√1/49-1/49</span>
<span>a=1/7</span>
4x^2-4=2(2x^2-2)
5t^2-20st+20s^2=5(t^2-4st+4s^2)
c-27cd^3=c(27d^3)
vu^3+vw^3=v(u^3+w^3)
t=(24-v)2,5 из формулы скорости
У= -3х-7;
х=-4;
у=-3 * (-4)-7;
у=12-7;
у=5.
ответ:5