7x+x (x-7) = (2x+5) (5-2x)
<span>7x+x²-7x = (5+2x) (5-2x)
</span><span>7x+x²-7x = 25-4x²
</span><span><span>x² +4x²-25=0
5x²-25=0
5(x²-5)=0
5≠0, значит х²-5=0
х²=5
х1=√5
х2=-√5
</span>
</span>
-cosx+cosx/2=1
1-2cos²x/2+cosx/2-1=0
-2cos²x/2+cosx/2=0
cosx/2(1-2cosx/2)=0
cosx/2=0⇒x/2=π/2+πn⇒x=π+2πn
cosx/2=1/2⇒x/2=+-π/3+2πn⇒x=+-2π/3+4πn
<u> 1 </u> >2
3x
х≠0
<u />1>2*3x
1>6x
6x<1
x<1/6
х∈(-∞; 0)U(0; 1/6)
х=-1 - наименьшее целое решение неравенства.