Выздоравливай)) Ваша задача решена ответ можете посмотрет в вложение
9.
...........= -2,4х+3,6у-6-6х-9у+6,5= - 8,4х - 5,4у+0,5
10.
![4\frac{2}{5} -(3-\frac{3}{10} )*3*\frac{1}{81} =4,4-(3-0,3)*3*\frac{1}{81}=\\ \\ 4,4-2,7*\frac{1}{27}=4,4-\frac{27}{10}* \frac{1}{27}=4,4-0,1=4,3\\ \\ \\ \\ 0,7*30-\frac{1}{2}:\frac{2}{67} =21- \frac{1}{2}*\frac{67}{2}=21-\frac{67}{4}=\\ \\21-16\frac{3}{4} = 21-16.75=4.25\\ \\ \\ 4.3>4.25](https://tex.z-dn.net/?f=+4%5Cfrac%7B2%7D%7B5%7D+-%283-%5Cfrac%7B3%7D%7B10%7D+%29%2A3%2A%5Cfrac%7B1%7D%7B81%7D+%3D4%2C4-%283-0%2C3%29%2A3%2A%5Cfrac%7B1%7D%7B81%7D%3D%5C%5C+%5C%5C+4%2C4-2%2C7%2A%5Cfrac%7B1%7D%7B27%7D%3D4%2C4-%5Cfrac%7B27%7D%7B10%7D%2A+%5Cfrac%7B1%7D%7B27%7D%3D4%2C4-0%2C1%3D4%2C3%5C%5C+%5C%5C+%5C%5C+%5C%5C+0%2C7%2A30-%5Cfrac%7B1%7D%7B2%7D%3A%5Cfrac%7B2%7D%7B67%7D+%3D21-+%5Cfrac%7B1%7D%7B2%7D%2A%5Cfrac%7B67%7D%7B2%7D%3D21-%5Cfrac%7B67%7D%7B4%7D%3D%5C%5C+%5C%5C21-16%5Cfrac%7B3%7D%7B4%7D++%3D+21-16.75%3D4.25%5C%5C+%5C%5C+%5C%5C+4.3%3E4.25+)
1) Пусть n=2
![1+ \frac{1}{ \sqrt{2} } \ \textgreater \ \sqrt{2} \\ \\ \sqrt{2}* (1+ \frac{1}{ \sqrt{2} } ) \ \textgreater \ \sqrt{2} *\sqrt{2} \\ \\ \sqrt{2} +1\ \textgreater \ 2 \\ \\ \sqrt{2} \ \textgreater \ 1 \\ \\](https://tex.z-dn.net/?f=1%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7B2%7D+%7D++%5C+%5Ctextgreater+%5C++%5Csqrt%7B2%7D++%5C%5C++%5C%5C++%5Csqrt%7B2%7D%2A+%281%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7B2%7D+%7D+%29+%5C+%5Ctextgreater+%5C+++%5Csqrt%7B2%7D+%2A%5Csqrt%7B2%7D++%5C%5C++%5C%5C++%5Csqrt%7B2%7D+%2B1%5C+%5Ctextgreater+%5C+2+%5C%5C++%5C%5C+%5Csqrt%7B2%7D+%5C+%5Ctextgreater+%5C+1+%5C%5C++%5C%5C)
верно
2)Пусть верно при n=k
![1+ \frac{1}{ \sqrt{2} } + \frac{1}{ \sqrt{3} } +...+ \frac{1}{ \sqrt{k} } \ \textgreater \ \sqrt{k} \\ \\](https://tex.z-dn.net/?f=1%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7B2%7D+%7D+%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7B3%7D+%7D+%2B...%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7Bk%7D+%7D+%5C+%5Ctextgreater+%5C++%5Csqrt%7Bk%7D++%5C%5C++%5C%5C+)
3)докажем, что верно при n=k+1
![1+ \frac{1}{ \sqrt{2} } + \frac{1}{ \sqrt{3} } +...+ \frac{1}{ \sqrt{k} } + \frac{1}{ \sqrt{k+1} } \ \textgreater \ \sqrt{k}+ \frac{1}{ \sqrt{k+1} } \\ \\](https://tex.z-dn.net/?f=1%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7B2%7D+%7D+%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7B3%7D+%7D+%2B...%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7Bk%7D+%7D+%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7Bk%2B1%7D+%7D+%5C+%5Ctextgreater+%5C+%5Csqrt%7Bk%7D%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7Bk%2B1%7D+%7D++%5C%5C++%5C%5C+)
![\frac{1}{ \sqrt{k+1} } -](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B+%5Csqrt%7Bk%2B1%7D+%7D+-+)
положительное число
![\sqrt{k} + \frac{1}{ \sqrt{k+1} } \ \textgreater \ \sqrt{k+1} \\ \\ \sqrt{k+1}*( \sqrt{k} + \frac{1}{ \sqrt{k+1} } )\ \textgreater \ \sqrt{k+1} * \sqrt{k+1} \\ \\ \sqrt{k(k+1)} +1\ \textgreater \ k+1 \\ \\ \sqrt{k^2+k} \ \textgreater \ \sqrt{k^2} ;k \geq 2 \\ \\](https://tex.z-dn.net/?f=+%5Csqrt%7Bk%7D+%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7Bk%2B1%7D+%7D+%5C+%5Ctextgreater+%5C++%5Csqrt%7Bk%2B1%7D++%5C%5C++%5C%5C+%5Csqrt%7Bk%2B1%7D%2A%28+%5Csqrt%7Bk%7D+%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7Bk%2B1%7D+%7D+%29%5C+%5Ctextgreater+%5C++%5Csqrt%7Bk%2B1%7D+%2A+%5Csqrt%7Bk%2B1%7D++%5C%5C++%5C%5C++%5Csqrt%7Bk%28k%2B1%29%7D+%2B1%5C+%5Ctextgreater+%5C+k%2B1+%5C%5C++%5C%5C++%5Csqrt%7Bk%5E2%2Bk%7D+%5C+%5Ctextgreater+%5C++%5Csqrt%7Bk%5E2%7D+%3Bk+%5Cgeq+2+%5C%5C++%5C%5C+)
верно
⇒
![1+ \frac{1}{ \sqrt{2} } + \frac{1}{ \sqrt{3} } +...+ \frac{1}{ \sqrt{k} } + \frac{1}{ \sqrt{k+1} } \ \textgreater \ \sqrt{k+1} } \\ \\](https://tex.z-dn.net/?f=1%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7B2%7D+%7D+%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7B3%7D+%7D+%2B...%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7Bk%7D+%7D+%2B+%5Cfrac%7B1%7D%7B+%5Csqrt%7Bk%2B1%7D+%7D+%5C+%5Ctextgreater+%5C+%5Csqrt%7Bk%2B1%7D+%7D+%5C%5C+%5C%5C+)
ч.т.д.
V1= 40000(кг)/7700(кг/м3)=5.2(м3)
m2=v2*p(стали)=1.3(м3)*7700(кг/м3)=10000 кг