S1=60кмV1=x-20S2=135кмV2=x+30t1=t260/(x-20)=135/(x+30)135x-2700=60x+180075x=4500x=60V1=60-20=40V2=60+30=90
ОДЗ: x^2+4x > 0
x(x+4) > 0
<u>(-беск.; -4) U (0; +беск.)</u>
x^2+1 > 0 --- х - любое
x^2+4x = x^2 + 1
4x = 1
x = 1/4
Xm^2-xn^2=x(m^2-n^2)=x(m-n)(m+n). 8p^2-8=8(p^2-1)= 8(p-1)(p+1).