24/60=2/5
80/X-80(Х+10)=2/5
Х^2 + 10Х-2000=0
Х=40
Х= -50
<span> ответ:40 км/час</span>
<em><u>1)
![\sqrt{21}](https://tex.z-dn.net/?f=+%5Csqrt%7B21%7D+)
≈ 4,582</u></em>
<em><u>
![\sqrt{80/4 }](https://tex.z-dn.net/?f=+%5Csqrt%7B80%2F4+%7D)
≈4,472</u></em>
<em><u>
![16 \\ 3](https://tex.z-dn.net/?f=16+%5C%5C+3)
≈5,333</u></em>
<em><u>3,5 - √80/2 - √21 - </u></em><u><em /></u><em><u>
![16 \\ 3](https://tex.z-dn.net/?f=16+%5C%5C+3)
</u></em>
<em><u>2)√35≈5,916 </u></em>
<u><em /></u><em><u>
![\sqrt{120/4}](https://tex.z-dn.net/?f=+%5Csqrt%7B120%2F4%7D+)
≈5,477</u></em>
<em><u>
![13 \\ 3](https://tex.z-dn.net/?f=13+%5C%5C+3)
≈4,3333</u></em>
<em><u>
![13 \\ 3](https://tex.z-dn.net/?f=13+%5C%5C+3)
- √120/2 - √35 - 6,5</u></em>
<em><u>3)√21≈4,582</u></em>
<em><u>3,5</u></em>
<em><u>
![3 \sqrt{2} = \sqrt{18}](https://tex.z-dn.net/?f=3+%5Csqrt%7B2%7D+%3D++%5Csqrt%7B18%7D+)
≈ 4,242</u></em>
<em><u>3,2</u></em>
<em><u>3,2- √(3,5)² -
![3 \sqrt{2}](https://tex.z-dn.net/?f=3+%5Csqrt%7B2%7D+)
- √21</u></em>
A1=10,2 a2=8,2
d=a2-a1=8,2-10,2=-2
a10=a1+9d=10,2-18=-7,8