240/x-240/(x-5)+4=0
x(x-5)≠0⇒x≠0,x≠5
240(x-5)-240*x+4x(x-5)
240x-1200-240x+4x²-20x=0
4x²-20x-1200=0
x²-5x-300=0
x1+x2=5 U x1*x2=-300
x1=-15 U x2=20
<span>-4(x+20+3(x-1)-2+5(x-2)+6)= -4(x+20+3x-3-2+5x-10+6)= -4х-100-12х+12+8-20х+40-24=-36х-64;
-36х-64=0
-36х=64
х= -<u>64</u>=- <u>16</u>= - <em>1</em> <u></u><u>7</u>
</span><span> 36 9 9 </span>
20+8х-20=14х+12
8х-14х=12
-6х=12
Х=-2
Угол DBE=углАВС=85(как вертикальные)
DEB=30(180-DEF)