\(\frac{x+1}{212}\)+\(\frac{x+2}{211}\)+\(\frac{x+3}{210}\)+\(\frac{x+4}{209}\)= -4
Tim x
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ta có
\(\frac{x+1}{212}+\frac{x+2}{211}+\frac{x+3}{210}+\frac{x+4}{209}=-4\)\(-4\)
\(\Rightarrow\left(\frac{x+1}{212}+1\right)+\left(\frac{x+2}{211}+1\right)+\left(\frac{x+3}{210}+1\right)+\left(\frac{x+4}{209}+1\right)=-4+4\)
=> \(\frac{x+1+212}{212}+\frac{x+2+211}{211}+\frac{x+3+210}{210}+\frac{x+4+209}{209}\) =\(0\)
=> \(\frac{x+213}{212}+\frac{x+213}{211}+\frac{x+213}{210}+\frac{x+213}{209}\)=\(0\)
=> (x+213) \(\left(\frac{1}{212}+\frac{1}{211}+\frac{1}{210}+\frac{1}{209}\right)\)=0
mà\(\left(\frac{1}{212}+\frac{1}{211}+\frac{1}{210}+\frac{1}{209}\right)\)\(\ne0\)
=>x+213=0 => x=-213
vậy x= -213
\(\frac{x+1}{212}+\frac{x+2}{211}+\frac{x+3}{210}+\frac{x+4}{209}=-4\)
\(\Rightarrow\frac{x+1}{212}+1+\frac{x+2}{211}+1+\frac{x+3}{210}+1+\frac{x+4}{209}+1=-4+4=0\)
\(\Rightarrow\frac{x+213}{212}+\frac{x+213}{211}+\frac{x+213}{210}+\frac{x+213}{209}=0\)
\(\Rightarrow\left(x+213\right)\left(\frac{1}{212}+\frac{1}{211}+\frac{1}{210}+\frac{1}{209}\right)=0\)
\(\Rightarrow x+213=0\Leftrightarrow x=-213\)
\(\left(X+5\right)-\left(X-9\right)=X+2\)\(2\)
\(=>X+5-X+9=X+2\)
\(=>\left(X-X\right)+\left(5+9\right)=X+2\)
\(=>0+14=X+2\)
\(=>14=X+2\)
\(=>X=12\)
(x+5)-(x-9)=x+2
x+5-x+9=x+2
x-x+14=x+2
12=x(cũng bớt mới về đi 2 đơn vị)
hoặc x=14-2suy ra x=12
\(\frac{25x-655}{95}-\frac{5\left(x-12\right)}{209}=\frac{89-3x-\frac{2\left(x-18\right)}{5}}{11}\)
\(< =>\frac{5x-131}{19}=\frac{1631-52x-\frac{38x-684}{5}}{209}\)
\(< =>\left(5x-131\right)209=\left(1631-52x-\frac{38x-684}{5}\right)19\)
\(< =>55x-1441=1631-52x-\frac{38x-684}{5}\)
\(< =>3072-107x=\frac{38x-684}{5}\)
\(< =>\left(3072-107x\right)5=38x-684\)
\(< =>15360-535x-38x-684=0\)
\(< =>14676=573x< =>x=\frac{14676}{573}=\frac{4892}{191}\)
nghệm xấu thế
\(\frac{8\left(x+22\right)}{45}-\frac{7x+149+\frac{6\left(x+12\right)}{5}}{9}=\frac{x+35+\frac{2\left(x+50\right)}{9}}{5}\)
\(< =>\frac{8x+176}{45}-\frac{41x+817}{45}=\frac{11x+415}{45}\)
\(< =>993-33x-11x-415=0\)
\(< =>578=44x< =>x=\frac{289}{22}\)
Có 1/3+3/35=44/105
Có 4/7+3/5+1/3=158/105
=> 44/105< x/210<158/105 MC: 210
=> 88/210< x/210< 316/210
Vậy x thuộc {89;90;91;92;...;315}
Ta có :
\(\frac{1}{3}+\frac{3}{35}< \frac{x}{210}< \frac{4}{7}+\frac{3}{5}+\frac{1}{3}\)
\(\Leftrightarrow\)\(\frac{70}{210}+\frac{18}{210}< \frac{x}{210}< \frac{120}{210}+\frac{126}{210}+\frac{70}{210}\)
\(\Leftrightarrow\)\(\frac{70+18}{210}< \frac{x}{210}< \frac{120+126+70}{210}\)
\(\Leftrightarrow\)\(\frac{88}{210}< \frac{x}{210}< \frac{316}{210}\)
\(\Leftrightarrow\)\(88< x< 316\)
\(\Rightarrow\)\(x\in\left\{89;90;91;...;314;315\right\}\)
Vậy \(x\in\left\{89;90;91;...;314;315\right\}\)
Chúc bạn học tốt ~
#)Giải :
1.
Ta có : \(\frac{n+1}{n+2}>\frac{n}{n+2}>\frac{n}{n+3}\)
\(\Rightarrow\frac{n+1}{n+2}>\frac{n}{n+3}\)
2.
a) \(x\left(104,5-14,1+9,6\right)=25\)
\(x\times100=25\)
\(x=25\div100\)
\(x=0,25\)
Bài 1 : Ta có :\(\frac{n+1}{n+2}>\frac{n}{n+2}>\frac{n}{n+3}\)
\(\Leftrightarrow\frac{n+1}{n+2}>\frac{n}{n+3}\)
Bài 2 : \(104,5\cdot x-14,1\cdot x+9,6\cdot x=25\)
\(\Leftrightarrow\left[104,5-14,1+9,6\right]\cdot x=25\)
\(\Leftrightarrow100\cdot x=25\)
\(\Leftrightarrow x=\frac{1}{4}\)
\(1+2+3+4+...+x=210\)
Số số hạng của dãy là : \((x-1):1+1=x\) số
Cho nên tổng của dãy đó là : \(\frac{x(x+1)}{2}=210\)
\(\Leftrightarrow x(x+1)=420\)
\(\Leftrightarrow x(x+1)=20\cdot21\)
\(\Leftrightarrow x=20\)
\(x-\frac{3}{4}=1-\frac{5}{6}\)
\(\Leftrightarrow x-\frac{3}{4}=\frac{1}{6}\)
\(\Leftrightarrow x=\frac{1}{6}+\frac{3}{4}=\frac{11}{12}\)
x = -213 nha bạn