A=1/3x60+1/6x57+1/9x54+...+1/60x3 phần 1/3+1/6+1/9+...+1/60
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Những câu hỏi liên quan
DT
4
26 tháng 2 2022
3.<,>,=
3-5/6....>...1+5/6 41/60-11/60....=....3/8+1/8
2/5+4/15....>...9/10-3/5 1/3-1/12..<....7/8-5/16
MD
0
AT
26 tháng 4 2018
heoheo lần sau bạn đánh = kí hiệu đi :(((
a/ \(\dfrac{x}{3}+\dfrac{2x-1}{6}=\dfrac{1}{2}\)
\(\Leftrightarrow2x+2x-1=3\)
<=> 4x = 4 <=> x = 1
Vậy x = 1
b/ \(\dfrac{3x+1}{2}+\dfrac{x-1}{3}=\dfrac{x-9}{6}\)
\(\Leftrightarrow3\left(3x+1\right)+2\left(x-1\right)=x-9\)
\(\Leftrightarrow9x+3+2x-2=x-9\)
\(\Leftrightarrow10x=-10\Leftrightarrow x=-1\)
Vậy pt có nghiệm x = -1
c/ \(\dfrac{x-1}{x-2}=\dfrac{x+3}{x+2}\) ĐKXĐ: \(x\ne\pm2\)
<=> \(\left(x-1\right)\left(x+2\right)=\left(x+3\right)\left(x-2\right)\)
\(\Leftrightarrow x^2+2x-x-2=x^2-2x+3x-6\)
\(\Leftrightarrow0x=-4\left(voly\right)\)
Vậy pt vô nghiệm
d/ \(\dfrac{3x-1}{3x+1}+\dfrac{x-3}{x+3}=2\) ĐKXĐ: \(\left\{{}\begin{matrix}x\ne-3\\x\ne-\dfrac{1}{3}\end{matrix}\right.\)
pt <=> \(\dfrac{\left(3x-1\right)\left(x+3\right)}{\left(3x+1\right)\left(x+3\right)}+\dfrac{\left(x-3\right)\left(3x+1\right)}{\left(3x+1\right)\left(x+3\right)}=\dfrac{2\left(3x+1\right)\left(x+3\right)}{\left(3x+1\right)\left(x+3\right)}\)
=> (3x-1)(x+3) + (x-3)(3x+1) = 2(3x+1)(x+3)
\(\Leftrightarrow3x^2+8x-3+3x^2-8x-3=6x^2+20x+6\)
\(\Leftrightarrow-20x=12\Leftrightarrow x=-\dfrac{3}{5}\left(tm\right)\)
Vậy pt có nghiệm x=....
e/ như ý d
Ta có: \(\frac{1}{3\times60}+\frac{1}{6\times57}+\cdots+\frac{1}{60\times3}\)
\(=2\left(\frac{1}{3\times60}+\frac{1}{6\times57}+\cdots+\frac{1}{18\times45}+\frac{1}{21\times42}+\frac{1}{24\times39}+\frac{1}{27\times36}+\frac{1}{30\times33}\right)\)
\(=\frac{2}{63}\times\left(\frac{63}{3\times60}+\frac{63}{6\times57}+\cdots+\frac{63}{30\times33}\right)\)
\(=\frac{2}{63}\times\left(\frac13+\frac{1}{60}+\frac16+\frac{1}{57}+\cdots+\frac{1}{30}+\frac{1}{33}\right)\)
\(=\frac{2}{63}\times\left(\frac13+\frac16+\cdots+\frac{1}{57}+\frac{1}{60}\right)\)
\(A=\frac{\frac{1}{3\times60}+\frac{1}{6\times57}+\cdots+\frac{1}{60\times3}}{\left(\frac13+\frac{1}{60}+\frac16+\frac{1}{57}+\cdots+\frac{1}{30}+\frac{1}{33}\right)}=1:\frac{2}{63}=\frac{63}{2}\)