Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
\(c,\Rightarrow234-x^2+5=230\Rightarrow x^2=9\Rightarrow\left[{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\)
\(d,\Rightarrow44\left(3^{x+1}-3^5\right)=0\\ \Rightarrow3^{x+1}-3^5=0\\ \Rightarrow3^{x+1}=3^5\Rightarrow x+1=5\Rightarrow x=4\\ e,\Rightarrow\left(x+1\right)\left(x+2\right)=666\cdot667\Rightarrow x+1=666\Rightarrow x=665\\ f,\Rightarrow\left(3-x\right)^{15x-30}=1=1^{15x-30}\\ \Rightarrow3-x=1\Rightarrow x=2\)
c) \(234-30^0\left(x^2-5\right)=230\)
\(\Rightarrow234-x^2+5=230\)
\(\Rightarrow x^2=9\Rightarrow x=\pm3\)
d) \(\Rightarrow44\left(3^{x+1}-3^5\right)=0\)
\(\Rightarrow3^{x+1}-3^5=0\)
\(\Rightarrow3^{x+1}=3^5\)
\(\Rightarrow x+1=5\Rightarrow x=4\)
e) \(\left(x+1\right)\left(x+2\right)=444222\)
\(\Rightarrow\left(x+1\right)\left(x+2\right)=666.667\)
\(\Rightarrow\left\{{}\begin{matrix}x+1=666\\x+2=667\end{matrix}\right.\)\(\Rightarrow x=665\)
f) \(\left(3-x\right)^{15x}:\left(3-x\right)^{30}=1\left(x\ne3\right)\)
\(\Rightarrow\left(3-x\right)^{15x-30}=1\)
\(\Rightarrow15x-30=0\Rightarrow15x=30\Rightarrow x=2\left(tm\right)\)
4/3.5+4/5.7+4/7.9+4/9.11
=4.(1/3.5+1/5.7+1/7.9+1/9.11)
=4.1/2.(2/3.5+2/5.7+2/7.9+2/9.11)
=2.(1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11)
=2.(1/3-1/11)
=2.8/33
=16/33
4/3.5+4/5.7+4/7.9+4/9.11
=4.2/2.3.5+4.2/2.5.7+4.2/2.7.9+4.2/2.9.11
=4/2.2/3.5+4/2.2/5.7+4/2.2/7.9+4/2.2/9.11
=4/2.(2/3.5+2/5.7+2/7.9+2/9.11)
=4/2.(1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11)
=2.(1/3-1/11)
=2.8/33
=16/33
Khoảng cách có rồi thì bạn áp dụng công thức : \(\frac{a}{m.n}=\frac{1}{m}-\frac{1}{n}\)(với n-m=a) là làm được
S=\(\frac{2}{5.7}+\frac{2}{7.9}+...+\frac{2}{93.95}+\frac{3}{95.98}+\frac{4}{98.102}+\frac{5}{102.17}+\frac{2012}{107..2119}\)
S=\(\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{93}-\frac{1}{95}+\frac{1}{95}-\frac{1}{98}+\frac{1}{98}-\frac{1}{102}+\frac{1}{102}-\frac{1}{107}+\frac{1}{107}-\frac{1}{2119}\)
S=\(\frac{1}{5}-\frac{1}{2119}\)
S=\(\frac{2114}{10595}\)
`4 / 7 xx [-5] / 6 xx 7 / 4 xx 12 / 5`
`= [ 4 xx (-5) xx 7 xx 12 ] / [ 7 xx 6 xx 4 xx 5 ]`
`= [ 4 xx (-5) xx 7 xx 6 xx 2 ] / [ 7 xx 6 xx 4 xx 5 ]`
`= -2`
4/7 × -5/7 × 7/4 ×12/5
=> -10/21 × 42/10
=> -420/210
=> -42/21
Đáp số: -42/21
LAN SAU BAN HOI MINK SE CAN THAN HON
Trả lời:
\(\frac{4}{7.9}+\frac{4}{9.11}+...+\frac{4}{107.109}\)
\(=\frac{2.2}{7.9}+\frac{2.2}{9.11}+...+\frac{2.2}{107.109}\)
\(=2.\left(\frac{2}{7.9}+\frac{2}{9.11}+...+\frac{2}{107.109}\right)\)
\(=2.\left(\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+...+\frac{1}{107}-\frac{1}{109}\right)\)
\(=2.\left(\frac{1}{7}-\frac{1}{109}\right)=2.\frac{102}{763}=\frac{204}{763}\)